Background.The aim of this pilot study was to evaluate the efficacy and the safety of lamivudine therapy in hepatitis B virus (HBV)-positive/DNA-positive renal transplant recipients.Methods.Six HBV DNA-positive cadaveric renal transplant recipients ranging in age from 49±6 years were administered lamivudine, at 100 mg/day for a period of at least 6 months, on a compassionate-use basis. Lamivudine is the(-) enantiomer of 3′-thiacytidine, which is known to be a potent inhibitor of HBV replication. All of the patients but one were on cyclosporine-based immunosuppression.Results.The mean serum creatinine was 134±44 μmol/L. The mean duration of HBV infection was 230±54 months (156-288). All of the patients but one had high serum alanine aminotransferase levels (122±52 IU/L; range, 45-243). Histological evaluation showed the presence of either chronic active hepatitis (n=4) or cirrhosis (n=2). All of the patients but one were hepatitis B e antigen negative/hepatitis B e antibody positive, but none were coinfected with either hepatitis C virus or hepatitis D virus.Conclusions.Lamivudine therapy was associated with (i) a normalization of alanine aminotransferase levels in four of five patients when these levels were increased at the beginning (n=5); (ii) a rapid disappearance of HBV DNA from the serum (detected by hybridization) in all of the patients; (iii) the negativity of HBV DNA by polymerase chain reaction in four patients; and (iv) no change in renal function and in proteinuria when present (one patient). Finally, no adverse effects were noted. When lamivudine therapy was stopped for four patients after 6 months, it was associated with a biochemical and virological relapse within the weeks that followed. Lamivudine therapy was therefore resumed for these patients.