The study aimed to evaluate the behavior of alpha-glutathione S-transferase (alpha-GST) in the serum of hemodialysis patients with hepatitis C virus (HCV) infection following treatment with high-dose IFN-alpha-2b. Ten patients with detected anti-HCV antibodies and HCV RNA by RT-PCR were selected and treated with high-dose interferon (IFN)-alpha-2b, 10 million units s.c. daily for 2 weeks followed by 3 times per week for 6 additional weeks. Blood samples were obtained from these patients at baseline for plasma alpha-GST and hepatic aminotransferases, Patients were monitored with weekly blood counts and monthly liver enzymes. Biochemical (normal alpha-GST and ALT) and virologic (negative HCV RNA by RT-PCR) responses were observed in 3 (30%) of the 10 patients. At the end of the follow-up (follow-up duration 44 weeks), 3 patients demonstrated long-term biological and virologic responses and 7 had relapses. In the nonresponders plasma AST and ALT approached normal levels on some occasions despite persistent viral RNA. In contrast to;transaminases alpha-GST remained distinctly elevated in nonresponders and provided a more clear distinction between the responders and nonresponders. In conclusion, plasma alpha-GST, as a sensitive and reliable marker of response, may have a role in the monitoring of hemodialyzed patients undergoing IFN-alpha-2b therapy.