The sensitivity and specificity of eight different' combined' HIV-1,-2 antibody EIA's were compared by investigating serial dilutions of 22 HIV-1 and 11 HIV-2 antibody-positive sera, as well as 520 HIV-negative donor sera. All eight EIA's detected our neat seropositive samples, however with marked differences in diluted samples. For routine purposes six out of seven HIV-EIA's (and possibly also a rapid test pack) proved to be suitable.