Background.The hepatitis C virus (HCV) quasispecies feature is important for HCV persistence. Most liver grafts are reinfected by HCV after liver transplantation (LTx).Methods.The degree of HCV polymorphisms during LTx was determined by single-strand conformation polymorphism (SSCP) analysis and direct sequencing of the HCV hypervariable region 1 (HVR1).Results.The number of HCV HVR1 SSCP bands in three patients decreased within 3 months after LTx as compared with before LTx. Direct sequencing of serial samples of one patient showed that the number of HVR1 polymorphic sites was lower at 1.5 months after LTx, and that the major sequence was identical to that before LTx. The number of both the HVR1 SSCP bands and the polymorphic sites after 3 months after LTx returned to a similar level as before LTx.Conclusions.Only a subset of the preexisting HCV variants replicates in the transplant liver graft. The limited immunological selective pressure within the first post-LTx period results in a homogenous HCV population that becomes more heterogenous after the first 3 months.