The first description on the serological heterogeneity in C. albicans was published by Hasenclever and Mitchell (1961). These workers revealed that this species could be classified into two serotypes, A and B, as judged from the results of agglutination assay between the cells of large number of C. albicans strains and anti-rabbit whole cell sera. These workers (1964) identified the chemical entity of antigen of C. albicans as a water-soluble mannan, based on its ability to inhibit the agglutination reactions Summers et al. (1964) reported that the mannans of C. albicans serotype B strains were more cross-reactive with the anti-whole cell serum of Saccharomyces cerevisiae than the mannans of serotype A strains. Tsuchiya and his co-workers undertook a serological classification of a variety of yeasts, based on agglutination assays among heat-killed yeast form cells and polyclonal anti-rabbit whole cell sera absorbed with the heat-killed whole cells of the other Candida strains. They reported the presence of 14 different serotypes in the seven medically important Candida species (Tsuchiya et al, 1955, 1974).