Incisional wounds of the same length and depth were made on tongue and dorsal skin of rats and the fine structural aspects of the responses of these were compared. Comparisons were made between the timing and degree of phagocytosis, the timing and rate of epithelial cell migration, of overall rate of healing, and of reformation of basal lamina and attachment complex in these two tissues. Phagocytic activity in epithelium and connective tissue of mucosa reached higher levels than in skin and the peak of activity in the epithelium of the mucosa was earlier than in the epidermis. Mononuclear phagocytes were active in phagocytosis, neutrophils showed little phagocytic activity. Epithelial migration was found to begin earlier in mucosa than in skin. Epithelialization of the wound and repair of supporting tissue were completed earlier. The same sequence in the renewal of ultrastructural components of the hemidesmosome-attachment complex was found in skin and mucosa, but was completed earlier at the mucosal site. Mechanical and physical as well as physiologic factors may play a role in determining the differing rates of repair in mucosa and skin.