The influence of hepatitis B virus infection, alcohol consumption, tobacco smoking and use of oral contraceptives on the risk of hepatocellular carcinoma (HCC) was evaluated in a hospital-based case-control study in Catalonia, in the Mediterranean coastal area of north-eastern Spain. A total of 96 HCC cases (86.5% of them with associated liver cirrhosis) and 190 age- and sex-matched controls were studied. The odds ratio of HCC and 95% confidence interval among hepatitis B surface antigen (HBsAg) carriers was 4.9 (1.3-21.9). The OR was not significantly elevated in smokers, and a marginally significant increased risk was found among users of oral contraceptives based on 6 female cases. There was a significant dose-response relationship between alcohol consumption and risk of HCC (chi 2 for trend: 24.3, p less than 0.001). Although hepatitis B infection was strongly associated with HCC, alcohol abuse leading to cirrhosis appears to be one of the main causes of HCC in this region.