Information obtained for all persons with the acquired immunodeficiency syndrome (AIDS) reported to the Centers for Disease Control, Atlanta, includes a question about employment in a health care or clinical laboratory setting. As of May 1, 1986, a total of 922 (5.5%) of 16,748 adults with AIDS reported employment in such settings. Ninety-five percent of these health care workers belonged to recognized high-risk groups for AIDS; the proportion with "no identified risk" has not increased with time. All AIDS patients (including health care workers) who do not belong to high-risk groups are referred for further investigation. Of 88 health care workers initially reported with no identified risk, ten were from countries where heterosexual transmission is believed to play a major role; additional information was unobtainable or incomplete for 17 individuals. Of 61 persons on whom interviews or other follow-up information was obtained, 44 (73%) were reclassified. Specific occupational exposures that could be implicated as the source of human immunodeficiency virus infection were not identified for any health care workers with AIDS. A review of surveillance data supports other studies indicating that the risk of human immunodeficiency virus transmission in the occupational setting is low.