A study was performed in order to determine the prevalence of anti-hepatitis C virus (HCV) antibodies, the risk factors for HCV infection and the markers of hepatic disease in a population of prisoners. Of 101 new prisoners admitted to a Norwegian national prison over a three month period, 70 were included in the study, of whom 32 (46%) were anti-HCV positive. Intravenous drug abuse was the predominant risk factor for HCV infection, although a history of tattooing was found by logistic regression analysis to be a significant risk factor independent of intravenous drug abuse. Most anti-HCV positive prisoners had a history of previous incarcerations. Among the anti-HCV positive subjects, increased alanine aminotransferase (> 50 U/l) was found in 23 (72%). HCV infection was the major cause of hepatic abnormalities in the study population. Only 15 (47%) of the anti-HCV positive prisoners reported knowledge of previous hepatic disease.