Chronic liver disease (CLD) is frequent in Somalia. In a case-control study, 116 in-patients with CLD were compared with the same number of age and sex matched controls. Demographic variables, use of drugs, symptoms and signs, serological markers for hepatitis B virus (HBV) and serum alpha-foetoprotein (AFP) were assessed. Hepatitis B surface antigen (HBsAg) was found in 44 cases of which 17 had antibodies to hepatitis D virus (anti-HD) and 7 had hepatitis B e antigen (HBeAg). Twenty-three controls were HBsAg-positive, of whom 3 had anti-HD and one HBeAg. Increased relative risks (95% confidence intervals in parentheses) were 2.5 (1.3-4.5) for HBsAg, 6.5 (1.7-21.5) for anti-HD, and 7.4 (0.9-66.5) for HBeAg. Despite the association between the presence of HBV markers and CLD, 62% of the cases had no markers indicating current HBV infection. This was reflected in the low risk attributable to chronic HBV infection (22.6%), which was lower than that in patients with CLD in other African populations with a high HBsAg carrier rate. The prevalence of HBV markers did not differ between cases with AFP greater than 100 ng/ml and those with AFP less than 100 ng/ml. The former were characterized by male predominance, shorter duration of symptoms, and larger mean liver size, indicative of malignancy. The mean age of HBsAg-positive cases with AFP greater than 100 ng/ml was significantly lower (by 7.7 years) than that of HBsAg-negative cases with AFP greater than 100 ng/ml. Among the CLD patients with AFP less than 100 ng/ml, 48 were HBsAg-negative. These cases differed significantly from the other 68 cases in that more were females (35% against 16%), more originated from an agricultural area (56% against 30%), and more were regular consumers of drugs (48% against 28%). In conclusion, factors as yet undefined play a considerable role in the causation of CLD in Somalia. The possibility of determining the role of hepatitis C virus (HCV) awaits the development of more specific assays for anti-HCV antibodies.