We performed a case-control study to evaluate the risk of hepatocellular carcinoma (HCC) for hepatitis C virus (HCV) infection. A total of 305 newly diagnosed HCC cases (80% males) and 610 subjects (81% males) unaffected by clinically evident hepatic disease admitted to the 2 main hospitals in Brescia, North Italy, were recruited as cases and controls, respectively. Among the 122 HCC cases positive for HCV RNA, genotype 1b was found in 83 patients (68%), genotype 2 in 36 (29.5%) and genotype 1a in 3 (2.5%). Among the controls, 15 were infected with genotype 1b and 15 with type 2. Analysis of HCV envelope 1 nucleotide sequence among 25 cases and 8 controls infected with genotype 2 showed subtype 2c in 96% of cases and in all controls, and subtype 2a in 1 HCC case. The odds ratio (OR) for HCV RNA positivity adjusted for hepatitis B virus (HBV) markers and alcohol intake was 26.3 [95% confidence interval (CI): 15.8-44], and it was higher for genotype 1b (OR = 34.2) than type 2 (OR = 14.4). The OR for HCV RNA was 35.6 (95% CI: 14.5-87.1) when the HBV markers were all negative and 132 (15.3-890) when HBsAg positivity was present; the OR was 26.1 (95% CI: 12.6-54.0) among subjects with alcohol intake of 0-40 g/day and increased to 62.6 (23.3-168) and 126 (42.8-373) with an alcohol intake of 41-80 and >80 g/day, respectively. In conclusion, synergism was found between HCV infection and HBV infection and alcohol intake in causing HCC.