The second-generation enzyme immunoassays (EIAs) for antibodies against human immunodeficiency virus (HIV) from three manufacturers (Abbott, Organon, Wellcome) and three anti-HIV confirmatory tests, i.e. Western Blot (WB, Biotech, Dupont), radioimmunoprecipitation assay (RIPA, CLB) and a competitive immunoassay (CIA, Abbott) were evaluated on a panel of 6,488 serum samples, which had previously been used for the comparison of seven first-generation EIAs. For the present study the panel was expanded with sequential serum samples from 12 individuals followed at 1- to 3-month intervals during seroconversion for anti-HIV. The second-generation EIAs and confirmatory tests were significantly more sensitive than the first-generation EIAs as was demonstrated by detection of 10- to 100-fold higher endpoint titers in anti-HIV-positive sera as well as by earlier detection of anti-HIV in 7-11 of the 12 subjects, who seroconverted. In all sera obtained during early HIV infection anti-gp 160/120env antibodies (WB, CIA) were found in addition to anti-p24 (WB, RIPA) and in serial twofold dilutions of these 'seroconversion samples' the new Abbott EIA and RIPA were significantly more sensitive than WB (p less than 0.05), whereas CIA and the new Organon EIA were significantly less sensitive than WB (p less than 0.05). The new Wellcome EIA was not statistically less sensitive than WB. The CIA was as sensitive as WB for antibodies to envelope proteins (gp41, gp160, gp120), but considerably less sensitive for core (p24) antibodies, as was shown in sera obtained during early as well as later clinical stages of HIV infection.(ABSTRACT TRUNCATED AT 250 WORDS)