AIM: To investigate the frequency of occult hepatitis B, the clinical course of hepatitis B virus (HBV) reactivation and reverse seroconversion and associated risk factors in autologous hematopoietic stem cell transplantation (HSCT) recipients.METHODS: This study was conducted in 90 patients undergoing autologous HSCT. Occult HBV infection was investigated by HBV-DNA analysis prior to transplantation,while HBV serology and liver function tests were screened prior to and serially after transplantation.HBV-related events including reverse seroconversion and reactivation were recorded in all patients. RESULTS: None of the patients had occult HBV prior to transplantation. Six (6.7%) patients were positive for HBV surface antigen (HBsAg) prior to transplantation and received lamivudine prophylaxis; they did not develop HBV reactivation after transplantation. Clinical HBV infection emerged in three patients after transplantation who had negative HBV-DNA prior to HSCT. Two of these three patients had HBV reactivation while one patient developed acute hepatitis B. Three patients had anti-HBc as the sole hepatitis B-related antibody prior to transplantation, two of whom developed hepatitis B reactivation while none of the patients with antibody to HBV surface antigen (anti-HBs) did so. The 14 anti-HBs- and/or anti-HBc-positive patients among the 90 HSCT recipients experienced either persistent (8 patients) or transient (6 patients) disappearance of anti- HBs and/or anti-HBc. HBsAg seroconversion and clinical hepatitis did not develop in these patients. Female gender and multiple myeloma emerged as risk factors for loss of antibody in regression analysis ( P < 0.05). CONCLUSION: Anti-HBc as the sole HBV marker seems to be a risk factor for reactivation after autologous HSCT. Lamivudine prophylaxis in HbsAg-positive patients continues to be effective.