Candida antibody tests for systemic candidiasis were conducted on 53 sera from patients with the disease and 170 sera from control patients by agar gel diffusion, counterimmunoelectrophoresis (CIE), latex agglutination, and whole-cell agglutination. The agar gel diffusion test and CIE had sensitivity, specificity, and efficiency of approximately 90%. The whole-cell agglutination test scored significantly lower, whereas the latex test scored in between. The agar gel diffusion test had the highest reproducibility and the whole-cell agglutination test the lowest in tests of identical sera by six independent laboratories. The agar gel diffusion and CIE tests make significant contributions to the diagnosis of systemic candidiasis.