The results of a summer 1989 nationwide mail survey of psychiatric hospital pharmaceutical services are reported and discussed. A simple random sample of 200 hospitals was selected from 600 psychiatric hospitals registered by the American Hospital Association. Questionnaires were mailed to the director of pharmacy at each institution. Usable responses were received from 114 hospitals, for a net response rate of 57%. Responses were categorized by hospital size, ownership status, geographic region, and average length of stay. Substantial differences were noted between government and nongovernment hospitals in the number and types of pharmaceutical services provided, as well as in the manner in which services are provided. Non-government hospitals generally appeared to offer more progressive pharmaceutical services. Psychiatric hospitals in western states appeared to offer more advanced clinical pharmacy services than institutions in other geographic areas. The survey established baseline data on the nature and extent of both clinical and distributive services in psychiatric hospital pharmacy departments.