We conducted a telephone survey of a random sample of office-based primary care physicians in Los Angeles County to determine their practice experiences with patients infected with the human immunodeficiency virus (HIV). Telephone interviews included questions related to the physicians' experiences evaluating patients for HIV infection during the past 6 months and the presence of HIV-infected patients in their practices. Those without HIV-infected patients were asked if this was because they had not encountered such patients, because those patients had died, or because the physicians had chosen to refer these patients elsewhere or the patients had gone elsewhere for care. Of physicians who participated in the survey, 78% had evaluated a patient for HIV infection in the past 6 months; 34% were currently providing primary care for infected patients; and 36% had elected to refer HIV-infected patients elsewhere, or their patients had elected to find other physicians. In all, 48% of physicians in the sample had elected not to care for, or said they would not provide care for, patients with HIV infection. Among Los Angeles County primary care physicians, 36% have refused to provide continuing care for HIV-infected patients and another 12% indicated their unwillingness to do so should such patients present themselves for care. As of 1991, the reservoir of primary care physicians in Los Angeles not yet involved with but willing to care for HIV-infected patients is relatively small (15%).