Few data are available on the mechanism by which oral ketoconazole reaches the stratum corneum and exhibits its antifungal activity. The rapid onset of effect and the isolation of ketoconazole from the sweat support the theory that this agent reaches its site of action through eccrine sweat secretion. However, passive diffusion from the bloodstream and sebum secretion may also account for the antimycotic effect at the level of the stratum corneum. Oral ketoconazole has been shown to be effective in a variety of cutaneous fungal infections. However, systemic antifungal therapy is best reserved for extensive infections or those resistant to topical therapy.