Interferon (IFN) therapy is the only treatment strategy for hepatitis C virus (HCV) infection after liver transplantation (LT), but prophylactic and treatable IFN therapy after LT has been shown to be insufficient due to the adverse effects of IFN and rivabirin. In this paper, we describe the disappearance of HCV after LT without IFN therapy in the presence of residual viremia on the day of LT.We herein report our findings since this is considered an important case for the anti-HCV strategy of post LT.A 60-year old woman with LC and HCC was referred to Nagasaki University Hospital in August 2004. After she underwent LT on February 18, 2005, we injected peg-IFN-α-2a the 11th time at 18 wk and HCV-RNA was still positive in the serum at LT. The serum HCV-RNA was negative one month after operation and subsequently dissolved 15 mo after operation without IFN therapy. As a result, we speculate that if HCV-RNA is positive while HCV core antigen is negative before LT, then it may lead to clearance of HCV after LT. Therefore long acting peg-IFN-α-2a is thus considered a potentially effective agent for the treatment of HCV-related cirrhosis before LT.