Background and aims: Herpesviruses infect the liver and cause minor hepatitis. Our aim is to verify the presence of herpesviruses in the liver from hepatitis C patients and the possible influence of these viruses in the liver disease. Methods: We searched for herpesvirus DNA in liver biopsies from patients with hepatitis C and from a control group without hepatitis by means of nested polymerase chain reaction. Serological investigations were carried out as well. Results: Thirty-four liver specimens from hepatitis C patients were examined, 12 of which (35.3%) were positive for at least one herpesvirus DNA, whereas among the 19 control specimens only two were positive (10.5%; P = 0.049). Liver biopsies from seven patients, three with acute hepatitis of unknown origin, three with non-alcoholic steatohepatitis and one with autoimmune hepatitis were also investigated and three positive samples were found. Conclusions: The prevalence of herpesvirus DNA was found higher in patients with hepatitis C than in individuals without hepatitis. The influence of herpesviruses on the clinical course of hepatitis C is considered. (C) 1999 Elsevier Science B.V. All rights reserved.