Nosocomial viral hepatitis, type B, is assuming increasing importance in the United States. The keystone to an effective hepatitis control program is surveillance of patients and personnel, especially in high-risk areas, namely dialysis units, hematology-oncology units, and laboratories. Measures to control infection are outlined for specific areas of the hospital. Data currently available suggest that employees who have persisting hepatitis B surface antigen (HBSAg) need not be removed from their positions unless they have been proved to disseminate infection. Future investigations should include methods to study: [a] the mechanisms of nonpercutaneous spread of hepatitis B virus, [b] the role of the individual with persisting HBSAg in the dissemination of hepatitis B virus, [c] the efficacy of hepatitis B immune globulin in high-risk areas, and [d] the effectiveness of various chemical and physical procedures in use for inactivation of hepatitis B virus using animal model systems.