Objective To study the influence factors for HBV reinfection following liver transplantation.Methods 92 cases of liver transplantation were enrolled for open non-randomized clinical study.Given conventional OLTx and immunosuppressive agents and antibiotics to prevent infection etc,patients are divided into lamivudine alone and HBIG combined with lamivudine group.Observation of postoperative liver function,HBV serum markers,HBV DNA in PBMC,YMDD and HBV S gene mutation,liver tissue IH etc.Results In 92 cases of liver transplantation with HBV-related liver disease,hepatitis B recurrence rate was 4.35%(4/92).In lamivudine group the HBV infection rate was 35%(7/20);In combined therapy group the HBV infection rate was 6.94%(5/72).With preoperatively negative HBV DNA negative the hepatitis B recurrence rate was 0;With preoperatively positive HBV DNA,the postoperative HBV infection rate was 17.39%(12/69),which had cases with S gene or YMDD mutation.In patients with negative HBV DNA before and after operation,the HBV re-infection rate was 11.11%(1/9);In 5 cases with preoperative HBV DNA positive,the HBV infection rate was 4/5 after LTx;before and after operation HBV DNA are positive,the HBV infection rate was 100%(3/3);the preoperative HBV DNA positive and postoperative HBV DNA negative,the HBV infection rate was 50%(1/2).Conclusion To prevent HBV infection after LTx,lamivudine group easily leads to HBV re-infection than HBIG combined with lamivudine group.Preoperative serum HBV DNA positive,preoperative and postoperative HBV YMDD and S gene mutation are the primary factors affecting the HBV re-infection after operation.HBV DNA positive in PBMC is the source of HBV re-infection,but also the factor of recurrence of hepatitis B.