Statement of Changes of Beneficial Ownership

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	OMB APPROVAL OMB Number: 3235-0287 Expires: January 31, 2005 Estimated average burden hours per response... 0.5
	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(f) of the Investment Company Act of 1940

1. Name and Address of Reporting Person ^* BVF PARTNERS L P/IL	2. Issuer Name and Ticker or Trading Symbol ARENA PHARMACEUTICALS INC [ ARNA ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director __ X __ 10% Owner _____ Officer (give title below) __ X __ Other (specify below) Indirect Beneficial Owner
(Last) (First) (Middle) 227 West Monroe Street, Suite 4800	3. Date of Earliest Transaction (MM/DD/YYYY) 10/17/2003
(Street) Chicago, IL 60606 (City) (State) (Zip)	4. If Amendment, Date Original Filed (MM/DD/YYYY)	6. Individual or Joint/Group Filing (Check Applicable Line) ___ Form filed by One Reporting Person _ X _ Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security (Instr. 3)	2. Trans. Date	2A. Deemed Execution Date, if any	3. Trans. 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)
1.Title of Security (Instr. 3)	2. Trans. Date	2A. Deemed Execution Date, if any	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Common Stock	10/17/2003		S		886768	D	$7.69	1376977 ⁽³⁾	I	See footnotes ⁽¹⁾ ⁽²⁾
Common Stock	10/17/2003		S		569218	D	$7.69	883884 ⁽⁴⁾	I	See Footnotes ⁽¹⁾ ⁽²⁾
Common Stock	10/17/2003		S		1455014	D	$7.69	2259351 ⁽⁵⁾	I	See Footnotes ⁽¹⁾ ⁽²⁾

*Table II - Derivative Securities Beneficially Owned ( e.g.* , puts, calls, warrants, options, convertible securities)**
1. Title of Derivate Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Trans. Date	3A. Deemed Execution Date, if any	4. Trans. 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		7. Title and Amount of Securities Underlying Derivative Security (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)
1. Title of Derivate Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Trans. Date	3A. Deemed Execution Date, if any	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)			11. Nature of Indirect Beneficial Ownership (Instr. 4)

Explanation of Responses:
( 1)	The shares reported in this response are beneficially owned by Biotechnology Value Fund, L.P., a Delaware limited partnership ("BVF, L.P.") (1,376,977 shares); Biotechnology Value Fund II, L.P., a Delaware limited partnership ("BVF2, L.P.") (883,884 shares); BVF Investments, L.L.C., a Delaware limited liability company ("Investments") (2,259,351 shares); and by BVF Partners L.P., a Delaware limited partnership ("Partners"), and by its general partner BVF Inc., a Delaware corporation ("BVF Inc."), which is also an investment advisor to Partners. Partners is the general partner of BVF, L.P. and BVF2, L.P. and is the manager of Investments. Pursuant to the operating agreement of Investments, Partners is authorized, among other things, to invest the funds of Ziff Asset Management, L.P., the majority member of Investments, in the shares of common stock described herein as being beneficially owned by Investments.
( 2)	Mark N. Lampert is the sole shareholder and sole director of BVF Inc., and is an officer of BVF Inc. This joint filing on Form 4 shall not be deemed an admission that Mark N. Lampert is, for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise, the beneficial owner of any equity securities covered by this joint filing. Mr. Lampert disclaims beneficial ownership of shares reported in this response, except to the extent that he has a pecuniary interest therein. Mr. Lampert is currently a director of Arena Pharmaceuticals, Inc.
( 3)	Shares beneficially owned by BVF, L.P.
( 4)	Shares beneficially owned by BVF2, L.P.
( 5)	Shares beneficially owned by Investments

Reporting Owners
Reporting Owner Name / Address	Relationships
Reporting Owner Name / Address	Director	10% Owner	Officer	Other
BVF PARTNERS L P/IL 227 West Monroe Street, Suite 4800 Chicago, IL 60606		X		Indirect Beneficial Owner
BIOTECHNOLOGY VALUE FUND L P 227 West Monroe Street, Suite 4800 Chicago, IL 60606				Direct Beneficial Owner
BIOTECHNOLOGY VALUE FUND II LP 227 West Monroe Street, Suite 4800 Chicago, IL 60606				Direct Beneficial Owner
BVF INVESTMENTS LLC 227 West Monroe Street, Suite 4800 Chicago, IL 60606				Direct Beneficial Owner
BVF INC/IL ONE SANSOME STREET, 31ST FLOOR SAN FRANCISCO, CA 94104		X		Indirect Beneficial Owner

Signatures
BVF Partners L.P., By: BVF Inc., its GP, By: /s/ Mark N. Lampert		10/21/2003
^** Signature of Reporting Person		Date
BIOTECHNOLOGY VALUE FUND, L.P. By: BVF Partners L.P., its GP, By: BVF Inc., By: /s/ Mark N. Lampert		10/21/2003
^** Signature of Reporting Person		Date
BIOTECHNOLOGY VALUE FUND II, L.P., By: BVF Partners L.P., its GP, By: BVF Inc., By: /s/ Mark N. Lampert		10/21/2003
^** Signature of Reporting Person		Date
BVF INVESTMENTS, L.L.C., By: BVF Partners L.P., its Manager, By: BVF Inc., By: /s/ Mark N. Lampert		10/21/2003
^** Signature of Reporting Person		Date
BVF INC., By: /s/ Mark N. Lampert		10/21/2003
^** 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 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).
Note:	File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
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.