With changes in the medical and surgical management of patients over the past 30 years, fungi have emerged as a major cause of human disease. Of the disseminated mycoses, candidiasis remains the most prevalent, with Candida albicans causing more invasive infections than any other fungus. However, the ever increasing pool of susceptible patients, particularly those with impaired immune function, has led to the emergence of opportunistic infection with less pathogenic yeast species and others previously regarded as food yeasts or harmless commensals. Moreover, molecular taxonomic studies have revealed new cryptic species amongst previously phenotypically delineated species, and many of these are not as yet included in commercial databases for phenotypic analyses. On occasion, the cryptic species that have been recognized differ in their susceptibility profiles from the closely related species, thus making their definitive identification clinically relevant.