Background.Hepatitis B virus infection originating from hepatitis B surface antigen-negative, hepatitis B core antibody (anti-HBc)-positive organ donors has been documented, and anti-HBc-positive donors have been excluded as liver donors. We assessed the prevalence of anti-HBc in UK organ donors and followed up recipients of organs from anti-HBc-positive donors for serological evidence of posttransplantation hepatitis B virus infection.Methods.Serum samples from 400 hepatitis B surface antigen-negative organ donors were tested for anti-HBc.Results.Only five (1.25%) of 20 sera in which anti-HBc was initially detected were confirmed as anti-HBc positive on further testing. Posttransplantation serum samples from four recipients of confirmed anti-HBc-positive organs showed no evidence of de novo hepatitis B infection.Conclusions.The poor specificity of some anti-HBc immunoassays was confirmed and suggests that donor exclusion on the basis of a single anti-HBc-positive result may result in the inappropriate loss of organs.