Diagnostic Products Corporation Appoints Sidney Aroesty as President

Los Angeles, CA (December 28, 2004)—- Diagnostic Products Corporation (NYSE:DP) announced today that the Board of Directors has unanimously appointed Sidney A. Aroesty as President of the Company, effective January 2, 2005.

Mr. Aroesty, 58, has been associated with DPC since 1978 and has served as a director since 1981. He has previously served as Senior Vice President, Operations and Chief Operating Officer. As President, Mr. Aroesty will be directly responsible for worldwide day-to-day operations. "Sid has played a key role in the Company's operations during his career at DPC and has helped to shape the decisions that have contributed to DPC's success," said Michael Ziering, CEO, Diagnostic Products Corporation. "Sid enjoys immense respect from the DPC team and his technical and managerial experience will enable us to carry out the strategic direction of our Company."

About Diagnostic Products Corporation

Diagnostic Products Corporation, founded in 1971, is the global leader dedicated exclusively to immunodiagnostics. DPC's product menu includes about 75 immunoassays and over 350 specific allergens and allergy panels. In addition, DPC addresses the chemistry and laboratory automation testing needs of its customers through partnerships with manufacturers of chemistry systems and reagents. The combined chemistry and immunoassay menu is one of the largest and most diversified available, covering most laboratory tests requested. DPC also designs and manufactures automated laboratory instrumentation, which provides fast, accurate results while reducing labor and reagent costs. DPC sells its products to hospitals, clinics and laboratories in more than 100 countries. Additional Company information can be found on DPC's website at www.dpcweb.com.

Except for the historical information contained herein, this press release contains forward-looking statements that involve risks and uncertainties that could cause actual results to differ materially. These factors include the effects of governmental and other actions relating to the FDA's decision that its Application Integrity Policy should be applied to the Company or relating to the Company's Chinese affiliate; the rate of customer demand for the Company's products; the Company's ability to successfully market new and existing products; its dependence on certain suppliers; domestic and foreign government regulation; its ability to keep abreast of technological innovations and to translate them into new products; competition; political and economic instability in certain markets including the movements of foreign currencies relative to the dollar; and other risks and uncertainties disclosed from time to time in the Company's SEC reports and filings.