LIMITED POWER OF ATTORNEY FOR
SECTION 16 REPORTING OBLIGATIONS



	KNOW ALL MEN BY THESE PRESENTS, that the undersigned hereby constitutes
and appoints Robert L. Van Nostrand the undersigned's true and lawful
attorney-in-fact and agent, with full power of substitution and
re-substitution, for the undersigned and in the undersigned's name, place
and stead, to execute and file with the appropriate offices on the
undersigned's behalf all Forms 3, 4 and 5 under Section 16 of the
Securities Exchange Act of 1934, as amened, with respect to the
undersigned's transactions in, and ownership of, the securities of OSI
Pharmaceuticals, Inc., a Deleware corporation, granting unto said
attorney-in-fact and agent full power and authority to do and perform each
and every act deemed requisite and necessary to be done in order to carry
out the foregoing as fully and to all intents and purposes as the
undersigned might and could do in person, hereby ratifying and confirming
all that said attorney-in-fact and agent or his substitute or substitutes
may lawfully do or cause to be done by virtue hereof.

	IN WITNESS
WHEREOF, the undersigned has executed this Power of Attorney as of the 18th
day of January, 2005.





									   Anker
Lundemose,M.D.,Ph.D,DSC
						Signature




Anker Lundemose,M.D.,Ph.D,DSC
						Print Name



STATE OF NEW
YORK

COUNTY OF SUFFOLK



	On this 18th day of
January, 2005, Anker Lundemose personally appeared before me, and
acknowledged that s/he executed the foregoing instrument for the purposes
therein contained.

	IN WITNESS WHEREOF, I have hereunto set my hand
and official seal.



									   Deborah A. Rocklein

						Notary Public



									   September 8, 2006

						My Commission Expires: