We have followed the candida antibody response in 115 patients with different types of candidiasis by discontinuous counterimmunoelectrophoresis using HS antigen to learn whether any early antibody response occurs in systemic candidiasis and whether there are differences in the antibody response in candidiasis involving different organ systems. We found that 23 of 32 (72%) patients with systemic candidiasis had a rise in antibody titer within the first 2 weeks of infection and that high titers were relatively insensitive indicators of infection. No differences were seen in the antibody response in different types of candidiasis. Patients with aspergillosis and torulopsosis had titer rises as well which were attributed to either inapparent candida infection or cross-reacting antibody. A rise in titer was not seen in any patient with candida colonization, bacterial or viral infection, or no infection in contrast to titers greater than or equal to 1/1 or greater than or equal to 1/8 which were seen in these conditions.