An enzyme immunoassay for the detection of antibodies against structural and nonstructural domains of the hepatitis C virus (EIA-2) was compared to a first generation test (EIA-1) that can only detect antibodies against one nonstructural antigen (c100). EIA-2 revealed elevated detection rates as assessed in high risk and patient populations as well as lower repeat reactive rates in volunteer blood donors. Research test systems proved an increase in apparent specificity.