During February 1988 a seroepidemiological survey of hepatitis A, B and D was performed in the Yemen Arab Republic. 879 sera were collected from 4 different areas; Sanaa, Hajja, Hodeidah and Taiz. The prevalence of hepatitis B surface antigen (HBsAg) was 12.7% (112/879) and some marker of hepatitis B infection was found in 45.5% (399/879) of study subjects. Only 2 (1.8%) of the 112 HBsAg positives were positive for antibody to delta hepatitis, and 9.7% (9/93) were positive for hepatitis B e antigen (HBeAg). Univariate analysis showed age, sex, qat chewing, blood transfusion, surgery and a past history of jaundice to be associated with hepatitis B infection. Using multivariate logistic regression analysis only, age (odds ratios 1.37 for HBsAg carriers and 1.51 for seropositives), a past history of jaundice (odds ratio 1.42), and combined history of blood transfusion and surgery (odds ratio 2.76) were independent predictors of infection. Hepatitis B appears to be a major health concern in the Yemen Arab Republic.