As more potent antibacterial drugs are used to combat infections and as more patients with impaired defenses against infection are treated, other organisms, like fungi, have become important pathogens. Fungi of all types may appear in this setting, but Candida species are the most common, usually beginning as an infection in the oropharynx. Although oropharyngeal candidiasis usually remains localized, it may spread elsewhere, leading to a fatal outcome. Controversy still exists regarding the best drug to prevent or treat oropharyngeal candidiasis, but clotrimazole given as a troche may be the best choice at the moment owing to its high clinical success rate, safety, cost effectiveness, and high patient acceptability. There remains a need for more randomized and controlled studies comparing the efficacy of nystatin, ketoconazole, and clotrimazole in high-risk patients in whom invasive candidiasis remains a frequent problem.