PIP: This article reviews the magnitude of human T-lymphotropic virus type III (HTLV-III) exposure, the outcome of such exposure, the economic burden of HTLV-III-related disease, and the social, ethical and public implications of the acquired immunodeficiency syndrome (AIDS) epidemic. The ELISA serum antibody test for HTLV-III is useful for diagnostic purposes, but does not indicate whether the person currently harbors the virus. Additional studies are needed to demonstrate that there are not antibodies to other viruses that cross-react in the test. Seropositivity from lymphadenopathy-associated virus (LAV) rose from under 10% in 1978 to 49% in 1984 among homosexual men attending a Colorado clinic for sexually transmitted diseases. In San Francisco, the prevalence of HTLV-III antibodies among homosexual men attending another such clinic reached 65% in 1984. Parenteral drug users have demonstrated similar increases in seropositity rates. The total number of persons in the US who are positive for HTLV_III antibodies is estimated to be at least 400,000 persons. Initial study results suggest that 4-19% of these seropositive individuals develop full-blown AIDS in 1-5 years. 40,000 new cases of AIDS are expected in the next 2 years. The AIDS epidemic has severely stressed the US health care system in terrms of its financial costs, use of resources, and effect on medical personnel. It is not unreasonable to estimate that AIDS will cost US society over half a billion dollars during the next calendar year. The grat social and economic burden associated with AIDS, and the effects of a positive ELISA test upon those tested, create a multitude of concerns. There is a need for a national coordinated health program on AIDS, as well as for special measures such as a national catastrophic fund for HTLV-III-related disease. Finally, the threasts to confidentiality posed by licensure of the HTLV-III antibody test must be recongnized.