A dot immunobinding assay for the detection of a circulating mannoprotein (MP) antigen of Candida species in the sera of neutropenic patients in a hematological setting is described. The technique is based on the use of a monoclonal antibody which recognizes an oligomannoside epitope shared by distinct MP of pathogenic Candida species. The sensitivity of the assay for antigen detection in serum was between 2 and 5 ng/ml, and MPs from Candida albicans, Candida tropicalis, Torulopsis glabrata, and Candida parapsilosis, but not Candida krusei, could be detected. A retrospective analysis of sera from patients with proven invasive candidiasis versus sera from controls (Candida-colonized and noncolonized subjects) revealed that the novel assay has sufficient sensitivity, specificity, and predictive values to be of potential diagnostic significance.