The authors investigated the dose-effect relation between alcohol drinking and hepatocellular carcinoma (HCC) in men and women separately, also considering hepatitis B and hepatitis C virus infections. They enrolled 464 subjects (380 men) with a first diagnosis of HCC as cases and 824 subjects (686 men) unaffected by hepatic diseases as controls; all were hospitalized in Brescia, northern Italy, in 1995-2000. Spline regression models showed a steady linear increase in the odds ratio of HCC for increasing alcohol intake, for values of >60 g of ethanol per day, with no substantial differences between men and women. Duration of drinking and age at start had no effect on the odds ratio when alcohol intake was considered. Former drinkers who had stopped 1-10 years previously had a higher risk of HCC than current drinkers did. The effect of alcohol drinking was evident even in the absence of hepatitis B or hepatitis C virus infection. In addition, a synergism between alcohol drinking and either infection was found, with approximately a twofold increase in the odds ratio for each hepatitis virus infection for drinkers of >60 g per day.