FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL OMB Number: 3235-0287 Expires: January 31, 2005 Estimated average burden hours per response... 0.5

(Print or Type Responses)

1. Name and Address of Reporting Person * SCHLEIFER LEONARD S   2. Issuer Name and Ticker or Trading Symbol REGENERON PHARMACEUTICALS INC [REGN] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) __X__ Director _____ 10% Owner __X__ Officer (give title below) _____ Other (specify below) President & CEO (Last) (First) (Middle) 777 OLD SAW MILL RIVER ROAD 3. Date of Earliest Transaction (Month/Day/Year) 05/01/2012 (Street) TARRYTOWN, NY 10591 4. If Amendment, Date 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 (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock               84,773 I by GRAT Common Stock               5,560 I by 401(k) Plan Common Stock 05/01/2012   S(1)   2,300 D $ 133.86 (2) 384,028 D   Common Stock 05/01/2012   S(1)   58,494 D $ 134.55 (3) 325,534 D   Common Stock 05/01/2012   S(1)   39,106 D $ 135.29 (4) 286,428 D   Common Stock 05/01/2012   S(1)   100 D $ 136.57 286,328 D

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
	Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB control number.		SEC 1474 (9-02)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Class A Stock

$ 0

(5)

(5)

Common Stock (6)

1,710,790

1,710,790

D

Class A Stock

$ 0

(5)

(5)

Common Stock (6)

22,275

22,275

I

by Trust for Son

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
SCHLEIFER LEONARD S 777 OLD SAW MILL RIVER ROAD TARRYTOWN, NY 10591	X		President & CEO

Signatures

/s/**Leonard S. Schleifer		05/02/2012
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(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).
(1)	Disposition/acquisition made pursuant to a plan intended to comply with Rule 10b5-1(c).
(2)	Represents volume-weighted average price of sales of 2,300 shares of Company stock on May 1, 2012 at prices ranging from $133.83 to $133.97. Upon request by the Commission staff, the Company, or a security holder of the Company, the reporting person will provide full information regarding the number of shares sold by the reporting person on May 1, 2012 at each separate price.
(3)	Represents volume-weighted average price of sales of 58,494 shares of Company stock on May 1, 2012 at prices ranging from $134.01 to $134.99. Upon request by the Commission staff, the Company, or a security holder of the Company, the reporting person will provide full information regarding the number of shares sold by the reporting person on May 1, 2012 at each separate price.
(4)	Represents volume-weighted average price of sales of 39,106 shares of Company stock on May 1, 2012 at prices ranging from $135.00 to $135.66. Upon request by the Commission staff, the Company, or a security holder of the Company, the reporting person will provide full information regarding the number of shares sold by the reporting person on May 1, 2012 at each separate price.
(5)	Exercisable date, exercise date, exercise price, purchase price, sales price, and/or expiration date is/are not applicable in this case.
(6)	Class A Stock of Regeneron Pharmaceuticals, Inc. ("Regeneron") converts to Common Stock of Regeneron on a one-to-one basis upon certain events.

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.

Potential persons who are to respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB number.