We performed a community-based study of 12 villages of southern Taiwan's A-Lein Township to investigate the epidemiology of hepatitis B and hepatitis C virus (HCV) infections. Of 6,095 patients, 13.8% were positive for hepatitis B surface antigen positive (HBsAg(+)) and 17.0% were positive for anti-HCV (anti-HCV(+)). Infection was found to be inversely related to educational level and to be directly related to the frequency of the receipt of parenteral injection for medical purposes. Risk factors for HBsAg positivity were male sex, age < or = 50 years, and a family history of hepatocellular carcinoma. Risk factors for HCV seropositivity were lower education level, frequent parenteral injections, blood transfusion, menial occupations, smoking, and age > 50 years. Therefore, risk factors for HBsAg(+) and anti-HCV(+) were different in these Taiwanese communities. Safe medical injections and improved health education for high-risk groups are imperative for preventing HCV transmission.