The relationship between liver cirrhosis and hepatocellular carcinoma is recognized, but quantification of risk is still uncertain. Therefore, we analysed data from a case-control study conducted in Italy between 1984 and 1997 on 499 cases of incident, histologically confirmed hepatocellular carcinoma and 1,552 controls in hospital with acute, non-neoplastic disease. Overall, 87 (17.4%) cases vs 10 (0.6%) controls reported clinical history of liver cirrhosis. The corresponding odds ratio (OR) was 27.5 (95% confidence interval (CI), 14.3-15.2) after allowance for sociodemographic factors, and 16.2 (95% CI, 7.9-32.9) after simultaneous allowance for all identified confounding factors, including alcohol consumption and clinical history of hepatitis. The association was of similar magnitude for subjects whose cirrhosis was diagnosed < 55 years (OR = 14.8) or at age 55 or over (OR = 20.0), and the multivariate OR was 33.7 < 5 years after diagnosis of cirrhosis, 37.3 between 5 and 9 years, and 7.6 (95% to 2.7-21.3) > or = 10 years since diagnosis of cirrhosis. The association was stronger in males (OR = 23.4) than in females (OR = 5.9), similar in various age groups, and somewhat stronger in more educated subjects (OR = 53.7), with history of hepatitis (OR = 33.1), reporting heavy alcohol consumption (OR = 24.9) or high body mass index (OR = 58.1), although the interaction term was significant only for sex. In terms of population attributable risk, 17% of hepatocellular carcinomas in this population can be attributed to clinical history of liver cirrhosis.