The sources of information are the results and methodology of studies that have been published or are in progress and the response of public officials and hospital executives to claims about the extent and burden of the costs of treating AIDS. The cost of treatment for AIDS will remain a central issue in social policy for many years. During the first 7 years of the epidemic, self-interested cost estimates were gradually replaced by grounded conjecture and findings from systematic research. By the summer of 1986, there was general consensus among experts on health care costs that AIDS was an expensive disease to treat, but not as costly as had been feared. Although it is not evident what policy will determine how the costs for AIDS treatment will be borne over the next few years, two scenarios, each with many variations, are plausible. Under one scenario, the demography of those at risk of AIDS infection and disease would remain the same. Under this scenario, the costs of AIDS would be paid under existing arrangements, with marginal changes. Under a second scenario, AIDS infection and cases of AIDS-related complex and AIDS would increase rapidly among white heterosexuals. Under this scenario, AIDS could be the impetus for restructuring our system of health-care financing. 9 appended tables from resource studies, 29 references.