SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                  SCHEDULE 13D
                                (Amendment No. 1)

                   Under the Securities Exchange Act of 1934*

                             Nabi Biopharmaceuticals
- --------------------------------------------------------------------------------
                                (Name of Issuer)

                     Common Stock, par value $0.10 per share
- --------------------------------------------------------------------------------
                         (Title of Class of Securities)

                                    629519109
- --------------------------------------------------------------------------------
                      (CUSIP Number of Class of Securities)

                                 Daniel S. Loeb
                                 Third Point LLC
                                 390 Park Avenue
                               New York, NY 10022
                                 (212) 224-7400
- --------------------------------------------------------------------------------
                  (Name, Address and Telephone Number of Person
                Authorized to Receive Notices and Communications)

                                   Copies to:
                            Michael A. Schwartz, Esq.
                          Willkie Farr & Gallagher LLP
                               787 Seventh Avenue
                             New York, NY 10019-6099
                                 (212) 728-8000

                                 April 27, 2006
- --------------------------------------------------------------------------------
                          (Date of Event which Requires
                            Filing of this Schedule)

If the filing person has previously filed a statement on Schedule 13G to report
the acquisition which is the subject of this Schedule 13D, and is filing this
schedule because of ss.ss. 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the
following box:  [ ]

NOTE: Schedules filed in paper format shall include a signed original and five
copies of the schedule, including all exhibits. See Rule 240.13d-7 for other
parties to whom copies are to be sent.

* The remainder of this cover page shall be filled out for a reporting person's
initial filing on this form with respect to the subject class of securities, and
for any subsequent amendment containing information which would alter
disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the Securities Exchange Act of
1934 ("Act") or otherwise subject to the liabilities of that section of the Act
but shall be subject to all other provisions of the Act (however, see the
Notes).






                                  SCHEDULE 13D


- --------------------------------------------         ---------------------------
CUSIP No.  629519109                                 Page 2 of 10 Pages
- --------------------------------------------         ---------------------------


- ----------- --------------------------------------------------------------------
    1       NAME OF REPORTING PERSON
            I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

            Third Point LLC                                I.D. #13-3922602
- ----------- --------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                                                                     (a) [ ]
                                                                     (b) [X]
- ----------- --------------------------------------------------------------------
    3       SEC USE ONLY

- ----------- --------------------------------------------------------------------
    4       SOURCE OF FUNDS*

            AF
- ----------- --------------------------------------------------------------------
    5       CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO
            ITEMS 2(d) or 2(e)  [ ]

- ----------- --------------------------------------------------------------------
    6       CITIZENSHIP OR PLACE OF ORGANIZATION

            Delaware
- --------------------- --------- ------------------------------------------------
                         7      SOLE VOTING POWER

                                0
                      --------- ------------------------------------------------
NUMBER OF SHARES         8      SHARED VOTING POWER
BENEFICIALLY OWNED
BY EACH REPORTING               5,150,000
PERSON WITH           --------- ------------------------------------------------
                         9      SOLE DISPOSITIVE POWER

                                0
                      --------- ------------------------------------------------
                         10     SHARED DISPOSITIVE POWER

                                5,150,000
- ----------- --------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH PERSON

            5,150,000
- ----------- --------------------------------------------------------------------
    12      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
            SHARES*     [ ]

- ----------- --------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            8.7%
- ----------- --------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON*

            OO
- ----------- --------------------------------------------------------------------







                                  SCHEDULE 13D


- --------------------------------------------         ---------------------------
CUSIP No.  629519109                                 Page 3 of 10 Pages
- --------------------------------------------         ---------------------------


- ----------- --------------------------------------------------------------------
    1       NAME OF REPORTING PERSON
            I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

            Third Point Offshore Fund, Ltd.
- ----------- --------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                                                                     (a) [ ]
                                                                     (b) [X]
- ----------- --------------------------------------------------------------------
    3       SEC USE ONLY

- ----------- --------------------------------------------------------------------
    4       SOURCE OF FUNDS*

            AF
- ----------- --------------------------------------------------------------------
    5       CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO
            ITEMS 2(d) or 2(e)  [ ]

- ----------- --------------------------------------------------------------------
    6       CITIZENSHIP OR PLACE OF ORGANIZATION

            Cayman Islands
- --------------------- --------- ------------------------------------------------
                         7      SOLE VOTING POWER

                                0
                      --------- ------------------------------------------------
NUMBER OF SHARES         8      SHARED VOTING POWER
BENEFICIALLY OWNED
BY EACH REPORTING               3,250,700
PERSON WITH           --------- ------------------------------------------------
                         9      SOLE DISPOSITIVE POWER

                                0
                      --------- ------------------------------------------------
                         10     SHARED DISPOSITIVE POWER

                                3,250,700
- ----------- --------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH PERSON

            3,250,700
- ----------- --------------------------------------------------------------------
    12      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
            SHARES*     [ ]

- ----------- --------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            5.5%
- ----------- --------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON*

            OO
- ----------- --------------------------------------------------------------------







                                  SCHEDULE 13D


- --------------------------------------------         ---------------------------
CUSIP No.  629519109                                 Page 4 of 10 Pages
- --------------------------------------------         ---------------------------


- ----------- --------------------------------------------------------------------
    1       NAME OF REPORTING PERSON
            I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

            Daniel S. Loeb
- ----------- --------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                                                                     (a) [ ]
                                                                     (b) [X]
- ----------- --------------------------------------------------------------------
    3       SEC USE ONLY

- ----------- --------------------------------------------------------------------
    4       SOURCE OF FUNDS*

            AF
- ----------- --------------------------------------------------------------------
    5       CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO
            ITEMS 2(d) or 2(e)  [ ]

- ----------- --------------------------------------------------------------------
    6       CITIZENSHIP OR PLACE OF ORGANIZATION

            United States
- --------------------- --------- ------------------------------------------------
                         7      SOLE VOTING POWER

                                0
                      --------- ------------------------------------------------
NUMBER OF SHARES         8      SHARED VOTING POWER
BENEFICIALLY OWNED
BY EACH REPORTING               5,150,000
PERSON WITH           --------- ------------------------------------------------
                         9      SOLE DISPOSITIVE POWER

                                0
                      --------- ------------------------------------------------
                         10     SHARED DISPOSITIVE POWER

                                5,150,000
- ----------- --------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH PERSON

            5,150,000
- ----------- --------------------------------------------------------------------
    12      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
            SHARES*     [ ]

- ----------- --------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            8.7%
- ----------- --------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON*

            IN
- ----------- --------------------------------------------------------------------






     This Amendment No. 1 (the "Amendment") amends the Schedule 13D filed on
April 17, 2006 (the "Schedule 13D") and is being filed on behalf of Third Point
LLC, a Delaware limited liability company (the "Management Company"), Third
Point Offshore Fund, Ltd., a Cayman Islands limited liability exempted company
(the "Offshore Fund"), and Daniel S. Loeb, an individual ("Mr. Loeb" and,
together with the Management Company and the Offshore Fund, the "Reporting
Persons"). Unless the context otherwise requires, references herein to the
"Common Stock" are to shares of common stock, par value $0.10 per share, of Nabi
Biopharmaceuticals, a Delaware corporation (the "Company"). The Management
Company is the investment manager or adviser to a variety of hedge funds and
managed accounts (such funds and accounts, collectively, including but not
limited to the Offshore Fund, the "Funds"). The Funds directly own the Common
Stock to which this Schedule 13D relates, and the Reporting Persons may be
deemed to have beneficial ownership over such Common Stock by virtue of their
ownership or the authority granted to them by the Funds to vote and to dispose
of the securities held by the Funds, including the Common Stock.


Item 3.   Source and Amount of Funds or Other Consideration.

     Item 3 of the Schedule 13D is hereby amended by deleting the first
paragraph thereof and replacing it with the following:

     The Funds expended an aggregate of approximately $24,467,453 of their own
investment capital to acquire the 5,150,000 shares of Common Stock held by them
(the "Shares"), and the Offshore Fund expended an aggregate of approximately
$15,456,831 of its own investment capital to acquire its 3,250,700 shares of
Common Stock. All Shares were acquired in open market purchases on the Nasdaq
National Market.


Item 4.   Purpose of Transaction.

     Item 4 of the Schedule 13D is hereby amended by adding the following
thereto:

     On April 27, 2006, the Reporting Persons sent to the board of directors of
the Company a letter elaborating on the points made by the Reporting Persons in
the Schedule 13D. The letter also stated the Reporting Person's belief that if
the Company sells or enters into partnering arrangements with respect to any of
its assets, any proceeds received by the Company as a result of such a
transaction should be distributed to the Company's stockholders.

     A copy of the letter is filed herewith as Exhibit 99.1 and is incorporated
herein by reference in its entirety.


                                       5



Item 5.   Interest in Securities of the Issuer.

     Item 5 of the Schedule 13D is hereby amended by deleting the entirety of
the text thereof and replacing it with the following:

     (a) As of the date of this Amendment, the Management Company beneficially
owns 5,150,000 shares of Common Stock. The Management Company shares voting and
dispositive power over such holdings with Mr. Loeb and with the Funds. The
Shares represent 8.7% of the 59,517,041 shares of Common Stock outstanding as of
March 24, 2006, as reported in the Schedule 14A filed by the Company on April 7,
2006.

     As of the date of this Amendment, the Offshore Fund directly beneficially
owns 3,250,700 shares of Common Stock, which represent 5.5% of the outstanding
shares of Common Stock. None of the other individual Funds owns a number of
shares of Common Stock representing more than 5% of such total.

     (b) The Management Company and Mr. Loeb share voting and dispositive power
over the 5,150,000 shares of Common Stock held directly by the Funds. The
Management Company, Mr. Loeb and the Offshore Fund share voting power and
dispositive power over the 3,250,700 shares of Common Stock held by the Offshore
Fund.

     (c) Schedule A hereto sets forth certain information with respect to
transactions by the Funds, at the direction of the Management Company and Mr.
Loeb, in the Common Stock since the most recent filing on Schedule 13D.

     Schedule B hereto sets forth certain information with respect to
transactions by the Offshore Fund, at the direction of the Management Company
and Mr. Loeb, in the Common Stock since the most recent filing on Schedule 13D.

     All of the transactions set forth on Schedule A and Schedule B were
effected in the Nasdaq National Market.

     Except as set forth above and on Schedule A and Schedule B, since the most
recent filing on Schedule 13D there were no transactions in the Common Stock
effected by the Reporting Persons, nor, to the best of their knowledge, any of
their directors, executive officers, general partners or members.

     (d) Other than the Funds which directly hold the Shares, and except as set
forth in this Item 5, no person is known to have the right to receive or the
power to direct the receipt of dividends from, or the proceeds from the sale of,
the Shares.

     (e) Not applicable.

                                       6




Item 7.  Material to be Filed as Exhibits.

   99.1  Letter, dated April 27, 2006, from the Management Company to the
         Company.

                                       7



                                   Schedule A
                                   ----------


                   (Transactions by the Funds in Common Stock
                  since the most recent filing on Schedule 13D)


Date            Transactions            Shares          Price Per Share ($)
- ----            ------------            ------          -------------------

4/27/06            BUY                  150,000             5.9760





                                   Schedule B
                                   ----------


               (Transactions by the Offshore Fund in Common Stock
                  since the most recent filing on Schedule 13D)


Date            Transactions            Shares          Price Per Share ($)
- ----            ------------            ------          -------------------

4/27/06            BUY                  92,900              5.9760





                                   SIGNATURES

     After reasonable inquiry and to the best of our knowledge and belief, the
undersigned certify that the information set forth in this statement is true,
complete and correct.


Dated: April 27, 2006


                                  THIRD POINT LLC



                                  By:   /s/ Daniel S. Loeb
                                        ----------------------------------------
                                        Name:   Daniel S. Loeb
                                        Title:  Chief Executive Officer




                                  THIRD POINT OFFSHORE FUND, LTD.



                                   By:   /s/ Daniel S. Loeb
                                        ----------------------------------------
                                        Name:   Daniel S. Loeb
                                        Title:  Director





                                  /s/ Daniel S. Loeb
                                  ----------------------------------------------
                                  Daniel S. Loeb




               [SIGNATURE PAGE TO AMENDMENT NO. 1 TO SCHEDULE 13D
                    WITH RESPECT TO NABI BIOPHARMACEUTICALS]



                          [Third Point LLC Letterhead]


VIA EMAIL AND FEDERAL EXPRESS

April 27, 2006

Mr. David L. Castaldi
Geoffrey F. Cox, Ph.D
Mr. Peter B. Davis
Mr. Richard A. Harvey, Jr.
Leslie Hudson, Ph.D.
Ms. Linda Jenckes
Mr. Thomas H. McLain
Mr. Stephen G. Sundovar

     c/o Mr. Thomas E. Rathjen
     Vice President, Investor Relations
     Nabi Biopharmaceuticals
     5800 Park of Commerce Boulevard, N.W.
     Boca Raton, Florida 33487

To the Board of Directors of Nabi Biopharmaceuticals:

As you should be aware, Third Point LLC filed a Schedule 13D last week in which
we disclosed an 8.4% ownership stake in Nabi, which we have subsequently
increased as of today. If you have not read our filing, and the demands that we
make therein, I strongly urge you to do so immediately. I'd also encourage each
of you to review a history of Third Point's prior "activist investments" to get
an idea of how we have approached similar situations in the past (i.e., when we
determine that a company has substantial asset value that is not reflected in
the stock price due to poor corporate management and board oversight). Any one
of these examples may serve as an object lesson for what the Board and Nabi
management may expect should we not hear promptly from Tom McLain in regards to
the demands made in our Schedule 13D and below.

I would like to expand on some issues raised in our 13D filing, as well as to
disclose certain disturbing issues not previously discussed.

1.   We are deeply concerned that the company intends to continue to use Lehman
     as its investment banker, as evidenced by Tom McLain's statements in a
     Sun-Sentinel article last week. Not only has Lehman presumably presided
     over, and advised on, many of the company's strategic missteps over the
     years, we are also concerned that the longstanding relationship between Mr.
     McLain and the Lehman investment bankers will prevent the company from
     receiving objective advice that will lead to the creation of maximum
     shareholder value. We have been informed by certain prospective buyers of
     Nabi's assets that Nabi's management is "hunkered down" with Lehman, and
     that certain parties felt stonewalled by both Lehman and Nabi's management
     during the alleged ongoing process




     to "explore strategic alternatives" for PhosLo. These same parties were
     apparently similarly stymied when attempting to contact Mr. McLain and/or
     Lehman in recent months to express interest in purchasing other Nabi
     assets. We have also heard that several well-regarded investment banks have
     recently attempted to call Nabi to pursue business relationships and were
     not even given the courtesy of a return call from the company. It seems to
     us that unless the "strategic alternative" being pursued by Lehman and the
     company is to entrench management and maintain the status quo (which would
     be supported by the apparent requirement that all participants in the
     PhosLo process sign restrictive and unusual standstill agreements), Lehman
     has failed to fulfill its fiduciary duty to Nabi's shareholders.
     Accordingly, we demand that Nabi immediately retain an investment bank
     other than Lehman, or in conjunction with Lehman, to explore strategies to
     maximize shareholder value. We do not believe that such a process would be
     run earnestly and objectively, based on the issues noted above, without
     involving a new investment bank.

2.   As we also noted in our filing, until a process to maximize shareholder
     value is undertaken, the company should refrain from selling or partnering
     on any major assets (unless extraordinary shareholder value would be
     created from such a transaction), as we believe that there are parties
     interested in purchasing the entirety of Nabi and that selling or
     partnering on assets could potentially diminish the interest of these
     parties. We also believe that all cash proceeds received by Nabi as the
     result of any asset sales or partnering going forward should promptly be
     paid to shareholders. Management and the board have demonstrated, over many
     years, their inability to turn valuable corporate assets into anything but
     shareholder value destruction and "cash burn." We have no reason to believe
     that this will change going forward. To the contrary, the $25 million "cash
     burn" in the first quarter of 2006, and accompanying management commentary
     congratulating itself for its enhanced focus on shareholder value creation,
     strikes us as both cautionary and delusional. As such, all proceeds from
     corporate dispositions or partnering should be distributed immediately to
     shareholders rather than left in the company for management to dissipate.

3.   We are outraged by both the employee retention and option acceleration
     programs that you recently approved. We believe that the retention program
     was (a) overly generous, both relative to what other similarly-situated
     companies have implemented and in light of the value destroyed by this
     management team; (b) too narrow in terms of the number of employees invited
     to participate, and too weighted towards rewarding the very managers whose
     poor performance is responsible for destroying value, when it is the
     scientific staff who have created the real value, are the ones worthy of
     reward and who should thus be the primary focus of any retention program;
     and (c) propitiously timed to profit insiders by following the release of
     disastrous fourth quarter results, which temporarily depressed the stock
     price, and coming just ahead of the release of the positive StaphVAX news.
     As for the decision to accelerate the vesting of all outstanding options,
     we could understand this decision if Nabi were a company reporting profits
     and therefore having a public valuation based on a multiple of those
     earnings. Sadly, however, these are not issues that Nabi need worry about,
     since the company, as currently managed, has no prospect of making money
     within any acceptable timeframe - which the just-released first quarter


                                      -2-




     results further reinforce. Thus, unvested options have been accelerated on
     behalf of company insiders with no plausible benefit to the stockholders.

In closing, I would like to remind the Board of its fiduciary duties to
represent the financial interest of Nabi's shareholders, not the pecuniary
interest of Nabi's management. Approving the use of incumbent investment bankers
who have not served shareholder interests well in the past, and approving option
and restricted stock programs that gratuitously enrich management and yourselves
at the expense of the company's shareholders, are exactly the types of actions
you are legally charged to avoid, not enable. Under your watch this company has
had a virtually unbroken record of poor quarterly results (which, not
surprisingly, you managed to extend in the first quarter), missed milestones and
trial failures - all leading to significant value destruction for the company's
shareholders. Should this somehow have escaped you, we will happily furnish you
with a timeline demonstrating the repeated disappointments and resultant
dreadful stock price performance.

The good news is that, notwithstanding chronic mismanagement, we believe that
Nabi today still has (a) significant and coveted assets, and (b) parties
interested in buying all or parts of Nabi. Hence, a properly managed sale
process could offer some redemption for Nabi's apparently negligent board by
recovering substantial value for its shareholders. The long-term strategic plan
currently contemplated by management is fraught with far too much execution risk
and uncertainty - especially given the track record of this company. Therefore,
these valuable assets should be monetized in the near-term for the benefit of
the company's owners - and in no case should proceeds from these transactions be
reinvested in high-risk development programs (i.e., your current plan), with
which you've had no tangible success throughout your tenure overseeing this
company.

To reiterate, we insist that new bankers be immediately retained and that a bona
fide public sale process be commenced immediately. Anything less than finally
creating substantial value for Nabi shareholders, rather than continually paying
lip service to it while acting otherwise, is completely unacceptable.

Sincerely,



Daniel S. Loeb
Chief Executive Officer
Third Point LLC


                                      -3-