Candida albicans is the most common fungal infection of the human oral mucosa, yet much remains to be understood with respect to the pathogenesis of the disease. Numerous difficulties are inherent in designing studies that use human beings as subjects. The use of various animal species in experimental contexts has helped to provide insight with respect to this condition. A variety of manipulations of the system can be performed, including altering the host immune response, the mucosal environment, or the systemic environment. In addition, organism-related factors can be examined in a more controlled setting. The information obtained from such studies could not be obtained in an in vitro situation.