AIM: To analyze whether the presence of anti-HBs in liver transplant recipients is effective in preventing HBV infection. METHODS: Twenty-three patients receiving anti-HBc positive liver were studied. Nine recipients were anti-HBc positive as a result of previous HBV infection. Of them, one also received HBV vaccine during the pre-liver transplantation period. Fourteen recipients were anti-HBs positive due to HBV vaccine administered during the pretransplant period. Liver biopsy was obtained in 10/14 anti-HBc negative/anti-HBs positive recipients and in 4/9 anti-HBc positive recipients. RESULTS: After a mean follow-up period of 46 months, 1 recipient with protective serum anti-HBs levels developed de novo HBV infection as a consequence of immune escape HBV mutants. Among the 14 vaccinated anti-HBc negative/anti-HBs positive recipients, 1/10 patients with available liver biopsy (10%) had liver HBV-DNA at 13 mo post-liver transplantation without serum viral markers and did not develop de novo HBV infection. The vaccinated anti-HBc positive recipient without HBV vaccine response was HBV-DNA positive in serum and liver, viral DNA was continuously negative in the following tests, so a spontaneous seroconversion was diagnosed. CONCLUSION: The presence of anti-HBs as a result of HBV vaccine or past HBV infection seems to be effective at protecting patients receiving livers from anti-HBc positive donors. However, the emergence of immune escape HBV mutants, which can evade the anti-HBs protection, should be considered as a risk of HBV infection. AIM: To analyze whether the presence of anti-HBs in liver transplant recipients is effective in preventing HBV infection. METHODS: Twenty-three patients receiving anti-HBc positive liver were studied. Nine recipients were anti-HBc positive as a result of previous HBV infection. Of them, one also received HBV vaccine during the pre-liver transplantation period. Fourteen recipients were anti-HBs positive due to HBV vaccine administered during the pretransplant period. Liver biopsy was obtained in 10/14 anti-HBc negative / anti- HBs positive recipients and in 4/9 anti-HBc positive recipients. RESULTS: After a mean follow-up period of 46 months, 1 recipient with protective serum anti-HBs levels developed no no HBV infection as a consequence of immune escape HBV mutants. Among the 14 vaccinated anti-HBc negative / anti-HBs positive recipients, 1/10 patients with available liver biopsy (10%) had liver HBV-DNA at 13 mo post-liver transplantation without serum viral markers and did not develop de novo HBV infection. The vaccinated anti-HBc positive recipient without HBV vaccine response was HBV-DNA positive in serum and liver, viral DNA was continuously negative in the following tests, so a spontaneous seroconversion was diagnosed. CONCLUSION: The presence of anti-HBs as a result of HBV infection or past HBV infection seems to be effective protecting patients receiving livers from anti-HBc positive donors. However, the emergence of immune escape HBV mutants, which can evade the anti-HBs protection, should be considered as a risk of HBV infection.