The Rees-Stealy Research Foundation (RSRF) Laboratory is a non-profit research facility with the mission of conducting applied biomedical research. The Foundation was established in 1938 by Drs. Rees and Stealy, founders of the Medical Group. Homer D. Peabody, Jr. M.D., Director of the Rees-Stealy Medical Group has served as the Foundation's Executive Director since 1972. The Laboratory originally was in the main Rees-Stealy building at 2001 Fourth Street, but moved to a 1905 two-story structure at the corner of Fourth and Hawthorn in 1968.

The primary research focus of the Laboratory is heart cell physiology, pharmacology, biochemistry, and molecular biology. Experiments at RSRF use isolated heart cells from the rat, human atrial and ventricular cells are also used in some studies.

An emphasis is also placed at the Laboratory upon the training of graduate and undergraduate students, an activity shared by all its professional staff. Undergraduate students from SDSU, USD, UCSD and local community colleges have participated in the research activities of the Laboratory.