Thrush is most frequently found in infants or debilitated patients with serious diseases such as a malignant neoplasm. Candida albicans is the causative organism in most cases, although C. tropicalis,1 C. pseudotropicalis,2 C. krusei,3 C. parapsilosis,4 and C. guilliermondi,5 have all been reported as pathogenic agents for man. The Candida are common saprophytes of the gastrointestinal tract and may assume a pathogenic role under certain circumstances. Candida infections may be increasing in frequency, and antibiotic and adrenal corticosteroid therapy have been implicated as a cause of this increase by many authors.6-8 Brown and Hazen's isolation of nystatin from Streptomyces noursei9 has given impetus to the study of Candida infections. This antibiotic is effective against Candida in vitro,10 and clinical reports are generally favorable. Little is known of the natural history of untreated thrush or of the efficacy of simple cleansing of the