To evaluate the prevalence of hepatitis C virus (HCV) infection in Greek renal transplant (RT) patients and its association with abnormal liver function tests (LFTs), serum anti-HCV was determined (Ortho-ELISA test system) in 206 RT and 245 haemodialysis patients (HD) as controls. The prevalence (10.2%) of anti-HCV in RT patients was significantly higher (P < 0.0001) than in the Greek general population (0.7%) and lower (P < 0.0001) than in the HD patients (23.8%), and was not related to the patients' age, post-transplant time or pre-transplant HD time. None of the anti-HCV RT patients was HBsAg+, whereas 13 (62%) and 12 (57%) of them were anti-HBsAg+ and anti-HBc+, respectively. The incidence of abnormal LFTs in anti-HCV+ HBsAg- and anti-HCV- HBsAg+ RT patients was similar. Our findings indicate that: (a) the prevalence of serum anti-HCV in the Greek RT population is high, although considerably lower than in HD pts; (b) anti-HCV+ RT patients have a high incidence of abnormal LFTs, comparable to that seen in HBsAg+ RT patients; and (c) in a substantial proportion of anti-HCV+ RT patients there is evidence of previous HBV infection.