BACKGROUND: The presence of low-level hepatitis B virus (HBV) DNA has been demonstrated in some hepatitis B surface antigen (HBsAg)-negative patients. This HBsAg-negative but HBV DNA-positive case has been named occult hepatitis B virus (OHBV) infection. The aim of this study was to determine the prevalence of OHBV in patients on maintenance hemodialysis. METHODS: Eighty patients who were on dialysis and were previously detected as HBsAg negative were recruited in the study. Thirty-two patients (40%) were female, and the mean age was 51.56 +/- 14.16 years (21-78 years). HBV DNA was searched for by the polymerase chain reaction method in the sera of all patients. RESULTS: Sixty-eight patients (85%) positive for at least 1 of the serological markers used for hepatitis B, 3 patients (3-75%) positive for only antibody to hepatitis B core antigen, and 33 patients (41.25%) positive for only antibody to HBsAg were identified. The prevalence of OHBV infection was found to be 1.25%. CONCLUSIONS: Even though the prevalence of OHBV infection was found to be low in patients undergoing dialysis, searching for HBV DNA, if possible, will be useful because there is contagiousness in OHBV infection, and activation of OHBV infection has been known to occur after immunosuppressive treatment.