The National Association of Public Hospitals and the Association of American Medical Colleges' Council of Teaching Hospitals conducted a detailed survey on hospital care to patients with acquired immunodeficiency syndrome (AIDS) in major US public and private teaching institutions in 1985. The 169 hospitals treating patients with AIDS that responded to the survey reported providing inpatient services to 5393 patients with AIDS. These patients accounted for 171205 inpatient days and 8806 inpatient admissions, with an average length of stay of 19 days. The average costs and revenue for patients with AIDS per day were $635 and $482, respectively, with Medicaid representing the most frequent third-party payer. The average inpatient cost per patient per year was $20 320. Using Centers for Disease Control estimates of 18 720 patients diagnosed as having AIDS and alive during any part of 1985, we estimate that the total cost of inpatient care for patients with AIDS was $380 million for that year. We also found significant regional and ownership differences in source of payment for patients with AIDS and regional differences in revenues received for AIDS treatment. Results indicate that the costs of treating patients with AIDS will profoundly affect major public and private teaching institutions, but that public teaching hospitals in states with restrictive Medicaid programs will be most adversely affected.