SEC Form 3

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person* Epstein David M. (Last) (First) (Middle) C/O OSI PHARMACEUTICALS, INC. 41 PINELAWN ROAD (Street) MELVILLE NY 11747 (City) (State) (Zip)	2. Date of Event Requiring Statement (Month/Day/Year) 04/01/2010	3. Issuer Name and Ticker or Trading Symbol OSI PHARMACEUTICALS INC [ OSIP ]
		4. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director 10% Owner X Officer (give title below) Other (specify below) Sr. VP and CSO, Oncology	5. If Amendment, Date of Original Filed (Month/Day/Year)
			6. Individual or Joint/Group Filing (Check Applicable Line) X Form filed by One Reporting Person Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock	14,246(1)	D

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Stock Option (Right to Buy)	05/01/2007(2)	04/30/2013	Common Stock	7,084(6)	$26.21	D
Stock Option (Right to Buy)	12/13/2007(3)	12/12/2013	Common Stock	4,000(6)	$37.74	D
Stock Option (Right to Buy)	12/12/2008(3)	12/11/2014	Common Stock	17,500(6)	$47.29	D
Stock Option (Right to Buy)	12/15/2010(4)	12/14/2019	Common Stock	11,250(6)	$35.4	D
Stock Option (Right to Buy)	12/16/2011(5)	12/15/2015	Common Stock	22,500(6)	$33.62	D

Explanation of Responses:

1. Consists of (i) 1,937 shares of OSI Common Stock, (ii) 2,500 shares of Restricted Stock, which vest on May 1, 2010, and (iii) 9,809 Restricted Stock Units, which vest over a period of 4 years from their respective dates of grant. Dr. Epstein will receive one share of OSI Common Stock upon the vesting of each Restricted Stock Unit.

2. 25% of the option became exerciseable one year after the date of grant and the remainder will vest ratably on a monthly basis over the succeeding 36 months.

3. 25% of the option became exerciseable one year after the date of grant and the remainder will vest ratably on an annual basis over the succeeding 3 years.

4. 25% of the option will become exerciseable one year after the date of grant and the remainder will vest ratably on an annual basis over the succeeding 3 years.

5. One third of the stock option grant will become exercisable on each of the third, fourth and fifth anniversaries of the grant date.

6. Includes only options with the same termination date.

Remarks:

Exhibit List: Exhibit 24--Power of Attorney

	/s/ Pierre Legault, attorney-in-fact for Dr. Epstein	04/09/2010
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 5 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
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