Chronic liver disease is a common complication of parenteral drug use, and liver cirrhosis is frequently seen in users of both parenteral drugs and alcohol. In 1978-83, we studied 88 parenteral drug users with sufficient evidence of chronic liver disease to warrant liver biopsy. Current alcohol abuse was noted in 63 (72%), and six (7%) were former alcohol abusers. Cirrhosis was found in 33 (38%). Hepatitis C antibody (anti-HCV) was detected in 86 (98%). Also, 40 of the anti-HCV positive sera were tested with recombinant immunoblot assay and all of these were reactive. All but one of the 31 patients with anti-HCV and cirrhosis were alcohol abusers. We conclude that parenteral drug users with chronic liver disease almost always have evidence of HCV infection.