From September 1988 to May 1991, 160 orthotopic liver transplantations were performed in our hospital. Twenty-four patients had end-stage cirrhosis caused by chronic non-A, non-B hepatitis. Antibodies against hepatitis C virus were documented before and after orthotopic liver transplantation in 13 patients. Studies using the polymerase chain reaction demonstrated hepatitis C virus RNA in the serum and liver tissue of 17 patients (10 of whom tested positive for hepatitis C virus antibodies) before orthotopic liver transplantation. Tissue samples taken from liver grafts during the operation were hepatitis C virus RNA negative in every case. Ten of these 17 patients had positive hepatitis C virus RNA findings in serum and liver biopsy specimens within the first month after surgery. One patient died of Mucor sepsis 2 mo after orthotopic liver transplantation. Another patient died of multi-organ failure 3 mo after a retransplantation. Two patients underwent retransplantation for graft rejection at 2 and 3 mo, respectively. One year after orthotopic liver transplantation, hepatitis C virus RNA was demonstrated in allograft biopsy specimens in 13 of 15 patients. Two patients remained hepatitis C virus RNA negative in repeated biopsies up to 12 mo. Mild portal and lobular hepatitis developed within 6 months of orthotopic liver transplantation in four patients and within 1 yr in five additional patients. The data suggest that persistent hepatitis C virus reinfects the allograft in most cases, but the risk of acute organ damage caused by hepatitis C virus reinfection is low.