The GAO reviewed AIDS population characteristics, service availability, and payment for services in New Haven, Baltimore, Philadelphia, New Orleans, and Seattle. It found that demand for certain AIDS services exceeded capacity and that the size of the AIDS population doubled nearly every year since 1981. AIDS populations ranged from those made up almost exclusively of homosexuals to those predominantly comprised of or related to intravenous drug users. Most cities, even those with primarily homosexual AIDS populations, expected growth in their intravenous drug cases. Hospital care was generally available for people with AIDS, but outpatient medical care provided by physicians and clinics was reaching capacity. In most communities, nursing homes did not admit people with AIDS. Many home and community-based services were not available to AIDS patients, and the lack of housing for people with AIDS was a serious problem in all five communities. Medicaid was the primary payer of AIDS hospitalization costs, financing 30 to 50 percent. The GAO determined that further research on AIDS service delivery costs is needed and that Federal support for AIDS service delivery has been limited. An appendix gives information on how the five communities developed AIDS services. 14 references, 9 tables, 2 figures.