A novel RNA virus of the Flaviviridae family has been discovered recently and designated hepatitis GB-C virus (GBV-C). Previous studies have reported that GBV-C is associated with posttransfusion hepatitis, chronic viral hepatitis, and cryptogenic hepatitis. However, the clinical significance of GBV-C infection has been questioned increasingly in patients not undergoing transplantation. To investigate whether GBV-C infection under immunosuppression affects the clinical or the histological outcome in liver transplant recipients, we determined the prevalence and incidence of GBV-C infections and the clinical and histological signs in patients after orthotopic liver transplantation (OLT). The presence of GBV-C was tested in sera from patients before and in regular intervals up to 6 years after OLT by nested reverse transcription-polymerase chain reaction using primers derived from the NS3 region. A total of 72 patients were studied. Before OLT, 8 of 72 (11.1%) patients were positive for GBV-C. After OLT, 7 of 8 (87.5%) remained positive. Of 64 patients who were negative for GBV-C before OLT, 23 became positive after OLT, resulting in a de novo rate of GBV-C infection of 35.9%. We could not detect a higher rate of histologically proven hepatitis in GBV-C-positive patients (29.1%) than in GBV-C-negative patients (14.6%, P > 0.057). Comparing GBV-C-positive with GBV-C-negative liver transplant patients, we could not find any differences in age, gender, liver function tests, number of blood transfusions, histological degree of hepatitis, or number of rejection episodes. Survival was not negatively influenced by GBV-C positivity. In conclusion, the presence of GBV-C did not influence the clinical or histological outcome in liver transplant patients.