SECURITIES AND EXCHANGE COMMISSION
Washington, D.C 20549

Schedule 13G/A

Under the Securities Exchange Act of 1934
(Amendment No. 12)

DIAGNOSTIC PRODUCTS CORPORATION

(Name of Issuer)

COMMON STOCK, NO PAR VALUE

(Title of Class of Securities)

252450-10-1

(CUSIP Number)

December 31, 2003

(Date of Event which Requires Filing This Statement)

     Check the appropriate box to designate the rule pursuant to which this Schedule is filed.

o Rule 13d-1(b)

o Rule 13d-1(c)

x Rule 13d-1(d)

*The remainder of this cover page shall be filed out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

Page 1 of 3

Schedule 13G

CUSIP No. 252450-10-1

1.	NAME OF REPORTING PERSON     LOUIS COLEN
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP.
	(a) o
	(b) o
3.	SEC USE ONLY
4.	CITIZENSHIP OR PLACE OF ORGANIZATION     U.S.A.
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5.	SOLE VOTING POWER: 1,478,605
		6.	SHARED VOTING POWER: -0-
		7.	SOLE DISPOSITIVE POWER: 1,478,605
		8.	SHARED DISPOSITIVE POWER: -0-
9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON     1,478,605
10.	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES
	o
11.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)     5.1%
12.	TYPE OF REPORTING PERSON     IN

Page 2 of 3

Item 1(a)	Name of Issuer: Diagnostic Products Corporation
Item 1(b)	Address of Issuer’s Principal Executive Offices:
	5700 West 96th Street
	Los Angeles, California 90045
Item 2(a)	Name of Person Filing: Louis Colen
Item 2(b)	Address: 2727 Krim Drive
	Los Angeles, CA 90064
Item 2(c)	Citizenship: U.S.A.
Item 2(d)	Title of Class of Securities: Common Stock
Item 2(e)	CUSIP Number: 252450-10-1
Item 3	Statement filed Pursuant to Rules 13d-1(b) or 13(d)-2(b) or (c): Not Applicable
Item 4(a)	Amount Beneficially Owned: 1,478,605 shares
Item 4(b)	Percent of Class: 5.1%
Item 4(c)	Number of shares as to which reporting person has:
	(i) sole power to vote or to direct the vote: 1,478,605     (ii) shared power to vote or to direct the vote: 0     (iii) sole power to dispose or to direct the disposition of: 1,478,605     (iv) shared power to dispose or to direct the disposition of: 0
Item 5	Ownership of 5% or Less of Class: Not Applicable
Item 6	Ownership of More than 5% on Behalf of Another Person: Not Applicable
Item 7	Identification and Classification of the Subsidiary which Acquired the Security Being Reported on by the Parent Holding Company: Not Applicable
Item 8	Identification and Classification of Members of the Group: Not Applicable
Item 9	Notice of Dissolution of Group: Not Applicable
Item 10	Certification: Not Applicable

     After reasonable 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.

Dated: February 2, 2004	/S/ Louis Colen
	Louis Colen

Page 3 of 3 -----END PRIVACY-ENHANCED MESSAGE-----