Background: Partial-thickness defects involving the vermilion and mucosa of the lip are difficult to repair surgically. Objective: The purpose of this study was to evaluate the cosmetic and functional effectiveness of second-intention healing in the repair of partial-thickness defects confined predominantly to the vermilion and mucosa of the lip. Methods: Thirteen patients with squamous cell carcinoma of the lip underwent Mohs micrographic surgery, which resulted in partial-thickness defects predominantly confined to the vermilion and/or mucosa of the lip. All defects were allowed to heal by secondary intention. Results: Twelve patients had good to excellent cosmetic results, and functional impairment was not noted in any of the patients. One patient whose defect extended to the cutaneous portion of the lip had deformation of the vermilion border. Conclusions: Second-intention healing yields good to excellent cosmetic and functional results for the repair of partial-thickness defects involving the vermilion and/or mucosa of the lip. Defects involving more than 2 mm of the cutaneous lip or defects extending deeper than the superficial portion of the orbicularis oris muscle may result in cosmetic or functional deformity or both if allowed to heal secondarily. (J Am Acad Dermatol 2002;47:893-7.)