In a cross-sectional study in Dar es Salaam, Tanzania, we determined the seroprevalence of markers for hepatitis A, B, C and E viruses and examined associated risk markers. Among 403 healthy adults, the seroprevalence of antibodies to hepatitis A virus was 99.0% (95% confidence interval: 97.5–99.7). Prior exposure to hepatitis C and E viruses was rare (hepatitis C: 0.7% (0.2–2.1); hepatitis E: 0.2% (< 0.1–1.4)). The prevalence of all markers of hepatitis B was 70.7% (66.0–75.1). Hepatitis B surface antigen was identified in 6.0% (3.9–8.7) of subjects. Independent predictors of hepatitis B infection identified by logistic regression included older age, male gender, Muslim religion and type of abode. Given the high prevalence of hepatitis B and the low prevalence of hepatitis C, the majority of chronic viral hepatitis is likely to be associated with hepatitis B. Control efforts should focus primarily on hepatitis B.