To evaluate viral hepatitis as a hazard in general dentistry, we surveyed participants in an annual health-screening program at the 1972 American Dental Association session. Of 1245 practitioners, 0.9 per cent were positive for hepatitis B surface antigen, and 12.7 per cent were antibody positive. Of those who had had clinical hepatitis while studying or practicing dentistry, 43 per cent were seropositive. The frequency of evidence for prior infection with hepatitis B virus increased uniformly with increasing years of professional experience. The proportion of seropositive dentists did not vary with geographic region of the United States, or size of community. Only 10.5 per cent recognized illicit self-injection among patients, and their infection rate was not increased. These data indicate an increased frequency of infection with hepatitis B virus among general dentists, and are compatible with relatively uniform endemicity of subtype/ad strans of that agent in the general population for several decades.