There have been no documented cases of acquired immunodeficiency syndrome (AIDS) in personnel after a prospectively recognized in-hospital blood exposure. To assess the frequency of such exposure the membership of the Association for Practitioners in Infection Control was surveyed in early June 1983. Thirty-three percent of the membership responded, accounting for 42% of U.S. hospitals with more than 250 beds. Respondents reported needlestick or other significant blood exposures to blood from patients with AIDS occurring in 157 instances and to blood from patients with lymphadenopathy syndrome in 43 instances. Nineteen and twenty of the exposures, respectively, occurred before July 1982. There are two bases for believing that AIDS will not pose a substantial risk to hospital workers: the lack of demonstrated in-hospital AIDS transmission to date and the recognition that other viruses besides the hepatitis B virus-viruses that seem to have less potential for in-hospital transmission-are equally plausible models of AIDS transmission.