SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549
                          ____________________________
                                Amendment No. 4
                                  Schedule TO
           Tender Offer Statement under Section 14(d)(1) or 13(e)(1)
                     Of the Securities Exchange Act of 1934
                          ____________________________
                            Mylan Laboratories Inc.
         (Name of Subject Company (Issuer) and Filing Person (Offeror))
                          ____________________________
                    Common Stock, par value $0.50 per share
                        (Titles of Class of Securities)
                          ____________________________
                                   628530107
                     (CUSIP Number of Class of Securities)
                          ____________________________

                              Edward J. Borkowski
                            Chief Financial Officer
                            Mylan Laboratories Inc.
                              1500 Corporate Drive
                         Canonsburg, Pennsylvania 15317
                                 (724) 514-1800
(Name, Address and Telephone Number of Person Authorized to Receive Notices and
                Communications on Behalf of the Filing Persons)
                          ____________________________
                                   Copies To:

                              Roger S. Aaron, Esq.
                             Eric L. Cochran, Esq.
                    Skadden, Arps, Slate, Meagher & Flom LLP
                               Four Times Square
                            New York, New York 10036
                                 (212) 735-3000


/_/   Check the box if the filing relates solely to preliminary communications
      made before the commencement of a tender offer.

Check the appropriate boxes below to designate any transactions to which the
statement relates: 
/_/   third-party tender offer subject to Rule 14d-1.
/X/   issuer tender offer subject to Rule 13e-4.
/_/   going-private transaction subject to Rule 13e-3.
/_/   amendment to Schedule 13D under Rule 13d-2.

Check the following box if the filing is a final amendment reporting the 
results of the tender offer: /_/   


                  This Amendment No. 4 amends and supplements the Tender Offer
Statement on Schedule TO ("Schedule TO") filed with the Securities and Exchange
Commission (the "Commission") on June 16, 2005, as amended and supplemented by
Amendment No. 1 to Schedule TO filed with the Commission on June 17, 2005,
Amendment No. 2 to Schedule TO filed with the Commission on July 11, 2005, and
Amendment No. 3 to Schedule TO filed with the Commission on July 15, 2005, by
Mylan Laboratories Inc., a Pennsylvania corporation ("Mylan" or the "Company"),
in connection with Mylan's offer to purchase for cash up to 48,780,487 shares
of its common stock, par value $0.50 per share, including the associated
preferred stock purchase rights (the "Common Stock"), or such lesser number of
shares of Common Stock as are properly tendered and not properly withdrawn (the
"Shares"), at a price not greater than $20.50 nor less than $18.00 per Share,
net to the seller in cash, without interest. Mylan's offer is being made upon
the terms and subject to the conditions set forth in the Offer to Purchase,
dated June 16, 2005 ("Offer to Purchase"), and in the related Letter of
Transmittal ("Letter of Transmittal") which, as amended or supplemented from
time to time, together constitute the offer.

                  All information in the Offer to Purchase and in the related
Letter of Transmittal is hereby expressly incorporated in this Amendment No. 4
to Schedule TO by reference in response to all of the applicable items in
Schedule TO, except that such information is hereby amended and supplemented to
the extent specifically provided herein.

ITEM 11. Additional Information.

Item 11 of the Schedule TO is hereby amended and supplemented by adding the
following:

         On July 17, 2005, the Company issued a press release announcing the
preliminary results of the tender offer, which expired at 12:00 midnight, New
York City time, on Friday, July 15, 2005. A copy of the press release is filed
as Exhibit (a)(5)(F) to this Schedule TO and is incorporated herein by
reference.

ITEM 12.          Exhibits.

Item 12 of the Schedule TO is hereby amended and supplemented by adding the
following:

         (a)(5)(F) Press release issued by Mylan on July 17, 2005.



                                   SIGNATURE

                  After due inquiry and to the best of my knowledge and belief,
I certify that the information set forth in this statement is true, complete
and correct.

                                            MYLAN LABORATORIES INC.


                                            By:  /s/EDWARD J. BORKOWSKI
                                                ------------------------------
                                            Name: Edward J. Borkowski
                                            Title: Chief Financial Officer


Date:  July 18, 2005



                               INDEX TO EXHIBITS


       Exhibit 
       Number           Document
       -------          --------

       (a)(1)(A)        Offer to Purchase dated June 16, 2005.*****
       (a)(1)(B)        Letter of Transmittal (including Guidelines of the
                        Internal Revenue Service for Certification of Taxpayer
                        Identification Number on Substitute Form W-9).****
       (a)(1)(C)        Notice of Guaranteed Delivery.****
       (a)(1)(D)        Letter to Shareholders, dated June 16, 2005.*****
       (a)(1)(E)        Letter to Brokers, Dealers, Banks, Trust Companies and 
                        Other Nominees.*****
       (a)(1)(F)        Letter to Clients for use by Brokers, Dealers, Banks, 
                        Trust Companies and Other Nominees.****
       (a)(1)(G)        Letter from Mylan Laboratories Inc. to Participants in 
                        its Profit Sharing 401(k) Plan.****
       (a)(5)(A)        Form of Summary Advertisement.*****
       (a)(5)(B)        Press Release issued by the registrant on June 16, 
                        2005.*****
       (a)(5)(C)        Press Release issued by the registrant on July 6, 
                        2005.***
       (a)(5)(D)        Press Release issued by the registrant on July 11, 
                        2005.***
       (a)(5)(E)        Press Release issued by the registrant on July 15, 
                        2005.**
       (a)(5)(F)        Press Release issued by the registrant on July 17, 
                        2005.* 
       (b)              Commitment Letter from Merrill Lynch Capital Corporation
                        and Merrill Lynch, Pierce, Fenner & Smith Incorporated, 
                        dated as of June 13, 2005.*****
       (d)(1)           Rights Agreement dated as of August 22, 1996, between 
                        the registrant and American Stock Transfer & Trust Co.,
                        filed as Exhibit 4.1 to Form 8-K filed with the SEC on 
                        September 3, 1996, and incorporated herein by reference.
       (d)(2)           Amendment to Rights Agreement dated as of November 8, 
                        1999, between the registrant and American Stock Transfer
                        & Trust Co., filed as Exhibit 1 to Form 8-A/A, filed 
                        with the SEC on March 31, 2000.
       (d)(3)           Amendment No. 2 to Rights Agreement dated as of August 
                        13, 2004, between the registrant and American Stock 
                        Transfer & Trust Company, filed as Exhibit 4.1 to the 
                        Report on Form 8-K filed with the SEC on August 16, 
                        2004, and incorporated herein by reference.
       (d)(4)           Amendment No. 3 to Rights Agreement dated as of 
                        September 8, 2004, between the registrant and American 
                        Stock Transfer & Trust Company, filed as Exhibit 4.1 to 
                        the Report on Form 8-K filed with the SEC on September 
                        9, 2004, and incorporated herein by reference.
       (d)(5)           Amendment No. 4 to Rights Agreement dated as of December
                        2, 2004, between the registrant and American Stock 
                        Transfer & Trust Company, filed as Exhibit 4.1 to the 
                        Report on Form 8-K filed with the SEC on December
                        3, 2004, and incorporated herein by reference.
       (d)(6)           Mylan Laboratories Inc. 1986 Incentive Stock Option 
                        Plan, as amended to date, filed as Exhibit 10(b) to 
                        Form 10-K for the fiscal year ended March 31, 1993, and
                        incorporated herein by reference.
       (d)(7)           Mylan Laboratories Inc. 1997 Incentive Stock Option 
                        Plan, as amended to date, filed as Exhibit 10.3 to Form
                        10-Q for the quarter ended September 30, 2002, and 
                        incorporated herein by reference.
       (d)(8)           Mylan Laboratories Inc. 1992 Nonemployee Director Stock
                        Option Plan, as amended to date, filed as Exhibit 10(l)
                        to Form 10-K for the fiscal year ended March 31, 1998, 
                        and incorporated herein by reference.
       (d)(9)           Mylan Laboratories Inc. 2003 Long-Term Incentive Plan,
                        filed as Appendix A to Definitive Proxy Statement on 
                        Schedule 14A, filed with the SEC on June 23, 2003, and 
                        incorporated herein by reference.
       (d)(10)          Executive Employment Agreement dated July 22, 2002, 
                        between the registrant and Robert J. Coury, filed as 
                        Exhibit 10.1 to Form 10-Q for the quarter ended June 30,
                        2002, and incorporated herein by reference.
       (d)(11)          Amendment No. 1 to Executive Employment Agreement dated
                        as of December 15, 2003, between the registrant and 
                        Robert J. Coury, filed as Exhibit 10.15(a) to Form 10-Q
                        for the quarter ended December 31, 2003, and 
                        incorporated herein by reference.
       (d)(12)          Executive Employment Agreement dated as of July 1, 2004,
                        between the registrant and Edward J. Borkowski, filed 
                        as Exhibit 10.27 to Form 10-Q/A for the quarter ended 
                        September 30, 2004 and incorporated herein by reference.
       (d)(13)          Executive Employment Agreement dated as of July 1, 2004,
                        between the registrant and Louis J. DeBone, filed as 
                        Exhibit 10.28 to Form 10-Q/A for the quarter ended 
                        September 30, 2004 and incorporated herein by reference.
       (d)(14)          Executive Employment Agreement dated as of July 1, 2004,
                        between the registrant and John P. O'Donnell, filed as 
                        Exhibit 10.29 to Form 8-K, filed with the SEC on 
                        December 3, 2004 and incorporated herein by reference.
       (d)(15)          Executive Employment Agreement dated as of July 1, 2004,
                        between the registrant and Stuart A. Williams, filed as
                        Exhibit 10.30 to Form 10-Q/A for the quarter ended 
                        September 30, 2004, and incorporated herein by 
                        reference.
       (d)(16)          Form of Employment Agreement dated as of December 15, 
                        2003, between the registrant and certain executive 
                        officers (other than named executive officers), filed 
                        as Exhibit 10.18 to Form 10 Q for the quarter ended  
                        December 31, 2003, and incorporated herein by reference.
       (d)(17)          Penederm Incorporated Employee Stock Option Plan 
                        incorporated by reference to Exhibit 4.1 to the 
                        Registration Statement on Form S-8, filed with the 
                        Commission on October 5, 1998, File No. 333-65329.
       (d)(18)          Penederm Incorporated 1994 Nonemployee Directors Stock 
                        Option Plan incorporated by reference to Exhibit 4.1 
                        to the Registration Statement on Form S-8, filed with 
                        the Commission on October 5, 1998, File No. 333-65327.
       (g)              Not applicable. 
       (h)              Not applicable.
         _________________

         *     Filed herewith.

         **    Previously filed on Amendment No. 3 to Schedule TO on July 15, 
               2005.

         ***   Previously filed on Amendment No. 2 to Schedule TO on July 11, 
               2005.

         ****  Previously filed on Amendment No. 1 to Schedule TO on June 17, 
               2005.

         ***** Previously filed on Schedule TO on June 16, 2005.





                                                            Exhibit (a)(5)(F)


FOR IMMEDIATE RELEASE

                                         CONTACTS:
                                         Patrick Fitzgerald (Public Relations)
                                         Mylan Laboratories Inc.
                                         724.514.1800

                                         Kris King (Investor Relations)
                                         Mylan Laboratories Inc.
                                         724.514.1800


                    MYLAN LABORATORIES ANNOUNCES PRELIMINARY
           RESULTS OF ITS MODIFIED "DUTCH AUCTION" SELF TENDER OFFER

PITTSBURGH, PA - July 17, 2005 - Mylan Laboratories Inc. (NYSE:MYL) today
announced the preliminary results of its modified "Dutch Auction" self tender
offer, which expired at 12:00 midnight, New York City time, on Friday, July 15,
2005. Mylan expects to accept for payment an aggregate of 51,282,051 shares of
its common stock at a purchase price of $19.50 per share. These shares
represent approximately 19% of the shares outstanding as of June 14, 2005.
Mylan has been informed by the depositary for the tender offer that the
preliminary proration factor for the tender offer is approximately 94%.

Based on the preliminary count by the depositary for the tender offer, an
aggregate of 54,647,714 shares were properly tendered and not withdrawn at or
below a price of $19.50, including 48,665,373 shares that were tendered through
notice of guaranteed delivery. The 51,282,051 shares expected to be purchased
are comprised of the 48,780,487 shares Mylan offered to purchase and 2,501,564
shares to be purchased pursuant to Mylan's right to purchase up to an
additional 2% of the outstanding shares as of June 14, 2005, without extending
the tender offer in accordance with applicable securities laws.

The depositary provided a preliminary count of 25,311,398 shares tendered at
prices between $19.75 and $20.50 per share that are expected to be returned to
shareholders. In addition, based on the preliminary count, 3,325,663 shares
were tendered at prices of $19.50 or below but are expected be returned to
shareholders as a result of proration.

The Company has also been informed by the depositary that there was a tender
received by notice of guaranteed delivery for 26,291,200 shares at or below a
price of $19.50 per share. While the exact identity of the shareholder
responsible for this tender has not been disclosed, the Company is aware that
entities controlled by Carl Icahn filed a form 13D with the Securities and
Exchange Commission on November 1, 2004 that reported ownership of
approximately the same number of shares. Based on the approximate 94% proration
factor, the Company expects to purchase 24,713,728 of the shares from that
tender.

The number of shares to be purchased, the price per share and the proration
factor are preliminary. The determination of the final number of shares to be
purchased, the final price per share and the final proration factor is subject
to confirmation by the depositary of the proper delivery of the shares validly
tendered and not withdrawn. The actual number of shares validly tendered and
not withdrawn, the final price per share and the final proration factor will be
announced following the completion of the confirmation process. Payment for the
shares accepted for purchase and return of all other shares tendered and not
accepted for purchase will occur promptly thereafter. For questions and
information about the tender offer, please contact the information agent,
Morrow & Co., Inc., toll free at 1-800-607-0088.

Under the terms of the tender offer, Mylan offered to purchase shares of its
common stock at a price not greater than $20.50 per share nor less than $18.00
per share, net to the seller in cash, without interest. Based on the final
number of shares tendered and the prices specified by the tendering
shareholders, Mylan will determine the lowest per share price within the range
that enables it to buy up to 48,780,487 shares of its common stock.


About Mylan Laboratories

Mylan Laboratories Inc. is a leading pharmaceutical company with three
principal subsidiaries, Mylan Pharmaceuticals Inc., Mylan Technologies Inc. and
UDL Laboratories, Inc., that develop, license, manufacture, market and
distribute an extensive line of generic and proprietary products.



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