Sixteen of 110 hemodialysis (HD) patients fulfilling criteria of non-A, non B hepatitis (NANBH), i.e. alanine aminotransferase (ALT) greater than 50 U/ml in the absence of both serologic markers for acute HBV and HAV infections and clinical evidence of another cause of hepatitis, were tested for the presence of antibodies against hepatitis C virus (anti-HCV) by enzyme immunoassay (Ortho, Diagnostics). All (100%) were anti-HCV-positive. There were 5 patients with a monophasic (M) rise pattern (1 or 2 ALT rises), and 11 cases demonstrated a polyphasic (P) rise elevation pattern (more than 2). The mean ALT value of the M group was 202.3 +/- 209 U/ml and that of the P group was 116.6 +/- 39.1 U/ml. The patients received a mean of 19.1 +/- 16.2 units of packed red cells during the follow-up period (69.9 months). Only 1 patient received no blood transfusion. Six patients had a past HBV infection and 3 became HIV-infected in the course of this study. The high rate of infection of hemodialysis patients with hepatitis C virus in our setting points to the need for improved control measures.