ABSTRACT
1. Infection of hepatitis A virus (HAV) was prevented with hepatitis A vaccine. High risk groups of HAV infection should be inoculated this vaccine because Japanese peoples less than 40 years old didn't have immunity for HAV. 2. Infection of hepatitis E virus (HEV) was scarcely observed in Japan. 3. Infection of hepatitis B virus (HBV) by blood transfusion was eradicated after the screening with anti-HBc antibody for blood donors. And maternal transmissions of HBV and infections of HBV in hospital were protected by HB-globulin and hepatitis B vaccine. 4. Infection of hepatitis D virus (HDV) was protected by HB-globulin and hepatitis B vaccine. 5. Infection of hepatitis C virus (HCV) by blood transfusion markedly decreased after the screening with anti-HCV for blood donors. We can't prevent a maternal transmission of HCV but its frequency is low (about 10%). And acute hepatitis C due to an infection of HCV in hospital can be prevented by the treatment with interferon in the Workmen's Accident Compensation Insurance.