Over a 4 1/2 year period (1973-77) 41 individuals in a village in eastern Switzerland (population 3000) were admitted to hospital because of acute hepatitis B. This hepatitis incidence was much higher than that in surrounding villages and that in the whole country. An epidemiological survey showed that one of the two general practitioners in the affected village was the source of infection. He had a chronic aggressive hepatitis associated with circulating hepatitis B surface and e antigen. No new cases of hepatitis B occurred in the village in the 3 years after his death.