Data from 219 hemodyalized patients receiving attention in our Hospital and other private centers in our city are shown. Mean age was 46.9 (range: 14-85), and 132 were male; mean time under dialysis was 20 months, and subjects received an average of 5 transfusions per patient year. Serological reactivity to HBs Ag, Anti HBs and IgG anti HBc by ELISA were investigated in all of them, and anti HCV by second generation enzimo-immunoassay (EIA II) in 73 HBe Ag/anti HBe system were determined in HBs Ag positive patients and those reactive to anti HCV (EIA II) were confirmed by LIA (immunoblotting of synthetic peptides LIA-TEK Organos Teknica). Recombinant anti HBV vaccine 40 mcg at 0-1 and six month were received by 81 cases without HBV markers in their sera and a protective response was considered when anti HBs titration of 10 mU/ml or more were obtained two months later. Prevalence for anti HBc and anti HBs were 38.8% respectively and that for HBs Ag was 21% with 78% of them reactive for HBs Ag. True reactivity for anti HCV (confirmed by LIA) was present in 35.6%, but it was 9.7% in our Hospital and 54.8% in private units (p < 0.0002). Anti HBs titration was done in 69/81 patients who received anti HBV vaccine, and a protective response in 49% were obtained; the other 12 patients underwent acute hepatitis B during the vaccination period.(ABSTRACT TRUNCATED AT 250 WORDS)