The risk of HBV and HCV liver infection in kidney graft recipients was evaluated in 35 patients. All were tested for anti-HBc, HBsAg, HBeAg, anti-HBs, Anti-HBe, anti-HCV (c-100-3 and c-100-3, c-22, 33-c), anti-HDV and anti-HIV by ELISA, and for HBV-DNA by hybridization. Liver biopsy, immunostaining for HBcAg and Knodell's hepatic inflammatory index were performed in 18. Mean time elapsing form transplant to inclusion was 20.7 months (range 1-108). HBsAg was the only marker searched for prior to transplant. Twenty six (74.2%) patients presented HBV and/or HCV markers, while 9 (25.8%) had none; 16 (45%) proved anti-HBc+, 6(17.1%) HBsAg+, (3 HBeAg+ and 3 anti-HBe+), 7 (20%) anti-HBs+ and 3 (8.5%) isolated anti-HBc. Anti-HCV (C-100-3) was positive in 9/32 (28.1%), while 2nd. generation anti-HCV was positive in 20/35 (57.1%) cases. No false positives for 1st. generation test were found. Both anti-HDV and anti-HIV were negative in all the sample. Raised aminotransferases were present in 13/30 (43.3%), 7 in anti-HCV+, one in HBsAg+ and 3 in HBsAg+/HCV+ cases, but normal in 17/30 (56.6%). History of Transfusion and Hemodialysis time showed no significant differences between anti-HCV+ and anti-HCV negative cases. Biopsy disclosed 10 chronic persistent hepatitis (CPH), one chronic active hepatitis (CAH) with cirrhosis, one inactive cirrhosis (Ci) 4 minimal lesions (MHL) and 2 normal. Seven CPH, 3 MHL. one normal and both cirrhosis cases proved anti-HCV+. HBsAg was positive in the single CAH, in 2 CPH and in one MHL.(ABSTRACT TRUNCATED AT 250 WORDS)