BACKGROUND In spite of the progress made in the prevention of transfusion transmitted infections over the last few years, transmission of HBV infection through transfusion of HBsAg negative blood has been documented. OBJECTIVE To assess the frequency and clinical significance of anti-HBc in multitransfused hemodialysis patients. METHODS One hundred and forty-three hemodialysis patients who had been receiving blood regularly with an average of 39.4 +/- 7.579 months on hemodialysis were enrolled in this study. HBV markers (HBsAg, anti-HBc, anti-HBs) were measured in these patients and in 100 healthy controls by the ELISA technique. The following data were obtained for all patients: socio demographic data, number of blood transfusions and some laboratory investigations. RESULTS In our patients, anti-HBc was positive in 9%, anti HBs in 7%, coexistant HbsAg/anti-HBc in 2.8% and anti HBc/anti HBs in 18.9%, meanwhile no patients were positive for HBsAg alone. In patients with only positive anti-HBc, the levels of anti-HBc were significantly related to abnormal results of liver function. In patients with positive anti-HBs/anti-HBc (n = 27), 18 patients had abnormal liver function, and 9 patients had normal liver function with no significant difference between them. CONCLUSIONS This study suggests that hepatitis B prevalence in our multitransfused hemodialysis patients is far in excess of that anticipated on the basis of HBsAg prevalence. Absence of HBsAg in the blood of hemodialyzed patients may not be sufficient to ensure lack of circulating HBV, and isolated positivity of anti-HBc may be a possible indicator of active hepatitis B infection.