Infection with human T-cell lymphotropic virus III (HTLV-III) is closely linked to the acquired immunodeficiency syndrome (AIDS). We evaluated the risk of nosocomial infection with HTLV-III by testing for antibodies to HTLV-III among hospital employees, including victims of needle-stick exposure, endoscopists, pathologists, and laboratory workers. Assays for antibody against the virus were performed by enzyme-linked immunosorbent assay and electrophoretic (Western blot) techniques. Although all 22 of our patients with AIDS and 6 of 7 with AIDS-related complex were found to have antibodies to HTLV-III when both assays were employed, none of the 85 employees with nosocomial exposure to specimens from patients with AIDS were positive for HTLV-III antibody. These studies must be regarded as preliminary, but they suggest that when current hospital isolation procedures are employed, the risk of nosocomial transmission of HTLV-III is low.