University of California-San Francisco Medical Group and Hill Physicians Medical Group, the largest IPA in its region, announced they are joining forces as of Jan. 1. The new relationship between 1,500-physician UCSF Medical Group and 2,600-doctor Hill Physicians was described in an Aug. 11 statement as an "affiliation" that will provide access to primary care and specialty doctors for about 20,000 HMO enrollees in San Francisco.