Hepatitis G virus (HGV) is a parenterally transmitted virus, frequently associated with hepatitis C virus infection. Hepatitis G virus RNA was detected by reverse transcription-polymerase chain reaction in the serum of 40 patients with chronic hepatitis C. Nine (22.5%) patients had evidence of hepatitis G virus viraemia. No significant epidemiological or virological differences could be demonstrated between subjects infected with both hepatitis G virus and hepatitis C virus and subjects infected with hepatitis C virus alone. Aminotransferase values were comparable between the two groups, whereas higher levels of cholestatic enzymes (P< 0.001) were reported in the hepatitis G virus/hepatitis C virus-positive patients. A liver biopsy was performed on all 40 patients no later than 6 months before recruitment. The mean histological activity index did not differ between hepatitis G virus-positive and hepatitis G virus-negative patients, whereas specific histological features such as macrovesicular steatosis, portal granulomas, and bile duct damage were more commonly observed among the coinfected patients. The results indicate that coinfection with hepatitis G virus probably does not have a significant effect on hepatitis C virus-induced hepatic damage.