In Sudan, the incidence of hepatocellular carcinoma (HCC) is high and increasing. Hepatitis B virus (HBV) and hepatitis C virus (HCV) are important risk factors of HCC. This study aims to assess the role of HBV and HCV infections in the incidence of HCC in 2 regions of Sudan. A case-control study was conducted in 1996-98 among 150 HCC patients and 205 controls from 2 regions in Sudan. Their demographic characteristics as well as food habits and chronic conditions have been investigated. In this study, 115 cases and 199 controls were tested for hepatitis B surface antigen (HBsAg) and for HCV antibodies. Strong positive associations were found between HBV or HCV, and HCC with odds ratios (ORs) 9.8 (95% CI 5.1-18.9) and 8.3 (95% CI 2.3-29.9), respectively. After adjustment for age, by logistic regression, the ORs for HBV and HCV were 16.1 (95% CI 7.4-34.9) and 4.5 (95% CI 1.1-18.6), respectively. Further adjustment for region, education level and job type did not appreciably affect the results. Given a prevalence of HBV and HCV of 7.0% and 1.5% among controls, about 57% of all HCC cases can be attributed to these viral infections. Hepatitis infections seem to be important risk factors for HCC in Sudan.