We have evaluated a new enzyme immunoassay (EIA) to measure IgG antibodies (Abs) to HIV in patients with AIDS, AIDS-related complex (ARC), AIDS contacts (AC), and low risk controls. Twenty-nine (94%) of 31 AIDS, 27 (96%) of 26 ARC, 12 (54%) of 22 AC, and 1 (2%) of 60 control patients were anti-HIV Ab positive by this assay. Positive results were confirmed by Western blot analysis. The EIA for anti-HIV evaluated in this study is sensitive and specific in identifying individuals who have been infected by this retrovirus.