Background The most frequently used therapy for post-transplantation recurrence of hepatitis B virus (HBV) infection is lamivudine, but this drug is associated with a high resistance rate due to YMDD mutant. In preliminary reports, adefovir dipivoxil (ADV) has been shown to have activity against lamivudine-resistant strains of HBV. However, clinical experience in treatment of HBV infection after liver transplantation (LT) is still not entirely clear. This study was aimed to evaluate the prophylactic efficacy of ADV plus hepatitis B immunoglobulin (HBIG) in patients with YMDD mutant before LT.Methods From March 2004 to March 2006, 16 patients with chronic hepatitis B had lamivudine-resistant YMDD mutants detected prior to liver transplantation and received treatment with ADV plus additional intramuscular HBIG after LT as prophylaxis against graft reinfection. Tests for liver function, serum HBsAg, anti-HBs (HBIG), HBeAg, anti-HBc,anti-HBe, HBV-DNA, and creatinine were assessed pre- or post-liver transplantation.Results The median follow-up of these patients post-liver transplantation was 19.4 months. Fifteen patients survived and one patient died of recurrence of hepatocellular carcinoma (HCC). There was significant difference (10.98% vs. 2.26%, P＜0.05) in YMDD mutant rate between the patients with HBV-DNA over 106 copies/ml and those with HBV-DNA less than 106 copies/ml. Fifteen patients (93.8%) had undetectable HBV-DNA at 4 weeks and 1 (6.3%) at 6 months after LT. No hepatitis B recurrence was detected by persistent testing of HBsAg, HBeAg, and HBV-DNA and no increase of serum creatinine level associated with ADV was observed in any of the patients.Conclusion ADV combined with intramuscular HBIG can effectively prevent patients with pre-transplantation YMDD mutant from HBV recurrence after LT.