In a district in England, seven patients in whom acute hepatitis B (AHB) developed between January and July, 1978, had had major surgery by the same gynaecological team within six months of onset. Hepatitis B surface antigen (HBsAg) at high titre, hepatitis B e antigen, and Dane particles were found in the serum of the team registrar. The HBsAg subtype of the registrar and patients was ad. A postal inquiry of family doctors revealed an additional patient who had been jaundiced and had probably contracted AHB within six months of major surgery performed by the same registrar. Among this registrar's patients AHB arose in 8 (5%) of 153 who had had major operations, but in none of 300 who had had minor operations and in none of 136 obstetric patients. No cases were found in 188 major-surgery, 425 minor-surgery, and 130 obstetric control patients. Infection was probably transmitted by sharp instruments after accidental puncture of the surgeon's glove and skin.