During the 1980s, the frequency of nosocomial candidiasis increased dramatically. This trend has continued into the 1990s, and Candida species remain a major cause of nosocomial infections. Although Candida albicans remains the most frequent cause of fungemia and hematogenously disseminated candidiasis, a number of reports have documented infections caused by other Candida species: C. tropicalis, C. glabrata, C. parapsilosis, C. krusei, and C. lusitaniae. Many of these infections arise from an endogenous source, and their frequency is influenced by the patient population, the various treatment regimens, and the antibiotics or other supportive care measures employed at specific institutions. Additional infections may be accounted for by exogenous acquisition via the hands of health care workers, contaminated infusates and biomaterials, and the inanimate environment. Ongoing investigation should help improve our understanding of the epidemiology of candidiasis and facilitate the development of rational preventive measures.