This project represents a series of studies of transfusion-associated hepatitis (TAH) in prospectively followed transfusion recipients undergoing open-heart surgery. The studies have sequentially shown the efficacy of adopting an all-volunteer donor system, testing for the hepatitis B surface antigen, utilizing the surrogate assays alanine aminotransferase (ALT) and anti-hepatitis B core antibody (anti-HBc), and testing for antibodies to the hepatitis C virus (HCV). Overall, the studies have shown a decline in TAH incidence from nearly 30 percent in the 1960s, to 10 to 20 percent in the 1970s, to 8 to 12 percent in the early 1980s, and to 4 to 5 percent in the late 80s. Since 1990, the study has focused on the impact of the introduction of donor screening assays to detect carriers of HCV. Following first-genera-tion anti-HCV testing, introduced in 1990, the rate of TAH fell from 3 to 4 percent to 1.5 percent. Since the introduction of more sensitive second- generation assays in 1992, we have followed over 650 recipients and the overall TAH rate has fallen to 0.2 percent while the rate of transfusion associated hepatitis C has fallen to zero. The overall rate reflects only a single mild case whose etiology is undetermined. Hence, in this approximately 30-year span, we have documented the virtual disappearance of TAH. - transfusion-associated hepatitis, posttransfusion hepatitis,hepatitis C virus, non-ABC hepatitis - Human Subjects