The hepatitis C virus infection is a worldwide public health problem. The virus can be transmitted by contaminated blood, blood products. The virus causes chronic liver disease, cirrhosis, hepatocellular carcinoma. No vaccine is currently available to prevent hepatitis C. The infection can be prevented by screening the donors, and universal precaution. nasocromial infection. Objective To analyse cost and benefit component for screening HCV in blood donors by using ELESA test at Thai Red Cross, National Blood Center. Design: A descriptive-quantitative study. Method: Data was collected from Thai Red Cross, National Blood Center and the medical cost for treatement of the patients admitted at King Chulalongkorn Memorial Hospital, were analyzed. The physician order in the medical records at King Chulalongkorn Hospital, for patients admitted for receiving the treatment for hepatitis C during the year 1998-2000 has been reviewed. Result: It was found that the benefit of screening process is much higher than its cost. The conventional treatment cost for HCV for all stages was 227,168 Conclusion The benefit cost ratio of hepatitis C virus screening process was 22.60. Treendous amount of benefit for cost will occur in the future due to the treatment of avoided cases.