­Infection with hepatitis C virus (HCV) is a major cause of chronic liver disease. On the other hand, Nosocomial transmission of HCV is a concern in haemodialysis (HD) units worldwide. In these patients, blood transfusions and long term dialysis are risk factors for transmission of HCV. Diagnosis of HCV infection is currently based on the detection of anti HCV antibodies by ELISA, and is confirmed by HCV RNA. The aim of the present study was to identify and detect the circulating non structural protein by using ELISA ,SDS-PAGE and Western blot techniques  and to evaluate the usefulness of the detection of HCV antigen using ELISA for therapeutic follow-up (at 0 times, 12, 24 and 48 weeks) in selected 10 positive HCV-RNA patients at 0 times . Serum samples of 75 chronic hepatitis C (CHC) patients, serum samples of 75 haemodialysis patients and 25 healthy individual's sera as a negative control were included in this study. HCV antigen was detected in these samples using ELISA and Western blotting techniques. Western blot analysis showing a single immune reactive band in serum of CHC and haemodialysis patients infected with HCV at 27-KDa. ELISA technique was applied to detect the 27-KDa antigen. The cutoff level of ELISA above or below which the tested sera were considered positive or negative was calculated and was found to be 0.28 Based on this cut off the HCV antigen was detected in 80 % of CHC patients and in 36 % of haemodialysis patients. While, it was found that all healthy individuals used as a control were 100 % negative for HCV antigen. Furthermore, detection of HCV-RNA using nested PCR and HCV-NS4 antigen using ELISA for pre-therapeutic and therapeutic (combined interferon (IFN) and ribavirin therapy) at 0 time, 12, 24 and 48 weeks in 10 HCV-infected persons undergoing treatment was studied. The detection of HCV-NS4 antigen for these 10 positive HCV-RNA samples at (12 weeks and 24 weeks) showed that (60 %) were responsive for treatment and it was found that (40 %) did not respond.