The range of human infections caused by the yeast Candida albicans and a handful of related species is considerable. They range from relatively trivial conditions such as oral and genital thrush to fatal, systemic superinfections in patients who are already seriously ill with other diseases. Interest in Candida infections, and in C. albicans in particular, has become huge in recent years as fatal infections have become more prevalent and new Candida-based pathologies have been recognized. There is now even a large pseudoscientific cult based on the notion that chronic allergy to Candida can cause all sorts of common illnesses. The medical importance of Candida infections and the scientific value of C. albicans as a model for fungal cellular development have stimulated enormous advances in our understanding of the epidemiology of candidosis, pathogenesis of the disease, and the genetics and biochemistry of C. albicans.