This study evaluated the epidemiology and impact of hepatitis G virus (HGV) infection in patients with chronic hepatitis B and C. Serum samples were obtained from 128 consecutive untreated patients with chronic hepatitis B (72 cases) or C (56 cases). The presence of HGV RNA was determined by PCR amplification of the 5'untranslated region; the sensitivity of the assays was ten template copy equivalents. The prevalence of HGV RNA in hepatitis B and C was found to be 25% and 34%, respectively. HGV-positive and HGV-negative patients did not differ with respect to risk factors for infection, age, sex, or alanine aminotransferase activity. Similarly, there was no difference in the severity of liver disease, as assessed with HAI score. In conclusion, we found a very high prevalence of HGV infection in chronic hepatitis B and C patients in Poland. Nevertheless, no evidence was found that HGV coinfection has any impact on the severity of the underlying disease.