BACKGROUND Several reports have shown the efficacy of prophylactic lamivudine treatment for hepatitis B virus (HBV) infection in liver and renal transplantations. No data are available, however, after lung transplantation. We report our experience with prophylactic lamivudine treatment in lung transplant recipients with HBV infection or when the donor was HBc antibody positive. METHODS All our 120 lung transplant recipients and their donors were routinely screened for HBV markers. All recipients who tested positive for hepatitis B surface antigen and negative for HBV-DNA, or had organs from donors who tested positive for hepatitis B core antibody, were treated prophylactically with lamivudine for 12 months after lung transplantation. Patients whose liver functions became abnormal during follow-up were tested for HBV serology and HBV-DNA. RESULTS Eleven of 120 lung transplant recipients (9.2%) were treated with prophylaxis lamivudine. Four recipients were hepatitis B surface antigen positive, and 7 recipients received organs from donors positive for HBc antibodies. Median follow-up after treatment was 24 months. All patients had normal alanine transaminase and undetectable levels of HBV-DNA before treatment. No side effects of lamivudine therapy were reported by any of the patients. Reactivation with alanine transaminase elevation and high HBV-DNA levels occurred in 2 patients. Both of them were recipients positive for hepatitis B surface antigen. In the first patient, lamivudine-resistant strain was detected and adefovir dipivoxil was started. In the other, reactivation developed 2 months after the end of lamivudine treatment. Lamivudine treatment was resumed, with rapid normalization of the HBV-DNA. CONCLUSIONS Use of lamivudine is considered safe for suppressing HBV infection after lung transplantation.