In the early 1990s, posttransfusion NANBH, mainly caused by HCV, was the most common serious complication of transfusions, occurring in 2-5 percent of transfusion recipients. About 50 percent of those infected developed chronic hepatitis, of whom, 10 to 20 percent developed cirrhosis. Hepatocellular carcinoma had been reported to occur in some. This study provided the first evaluation of the effectiveness of donor screening for anti-HCV by the then recently licensed HCV antibody test and surrogate markers of NANBH. It also provided a precise estimate of the risk of transfusion-transmitted HCV. The results allowed examination of risk factors for HCV infected donors who were seronegative at the time of donation.