Careful interviewing of alcoholics who wish to undergo alcohol withdrawal programmes reveals that some are past intravenous drug abusers. As these two potentially hepatotoxic types of substance abuse could cause liver disease or influence its clinical course, we studied biological, histological and virological features in 26 alcoholics with a past history of intravenous (i.v.) drug abuse, compared with paired controls (alcoholics without i.v. drug abuse). There were no differences with regard to routine liver test results. In contrast, the former drug abusers had a significantly higher prevalence of serum markers of hepatitis C (76.9%) and hepatitis B viruses (76.9%) than the other patients (16.7 and 12.5%, respectively). Eight patients, all of whom were HBs Ag negative, were positive for serum HBV-DNA; three were former drug abusers and five were not, giving an overall prevalence of HBV markers in the two groups of 80.8 and 25%, respectively. Two former drug abusers had anti-HIV antibodies and one had anti-hepatitis delta virus antibodies. Ten of the 17 former drug abusers who underwent liver biopsy had histological signs of viral infection. These data underline the need for careful interviews of alcoholic patients, together with serological tests for viral infections and histological analysis of the liver, as some will have liver-damaging viral diseases and may be candidates for anti-viral (i.e. interferon) treatment.