A 41-year-old woman became ill with acute hepatitis B after gynecological surgery performed by a surgeon who was hepatitis B surface antigen positive. The surgeon was positive for hepatitis B e antigen, and HBV DNA concentrations in the serum, saliva, and sweat of the surgeon were very high. HBV genotype and partial HBV DNA sequences from the HBV-infected surgeon were identical to those in the HBV-infected patient. Extensive research by the committee including infection control and prevention specialists judged the source of infection to be a surgeon infected with HBV. Transmission of HBV from a healthcare worker to patients who are not immune to HBV can actually happen. This case report illustrates the importance of a stringent policy of a nationwide HBV universal vaccination program.