Actinic cheilosis is a chronic degenerative disorder primarily of the lower lip caused by long-term exposure to sunlight. It is premalignant and usually occurs in fair-skinned men over 40 years of age. Reducing exposure to sunlight is the single most important measure in preventing actinic cheilosis. Diagnosis is predicated on histological examination of biopsy specimens. Topical chemotherapy may be used in early lesions. Prophylactic ablation or vermilionectomy may be performed in cases where malignant transformation has not yet occurred. The treatment of malignancy is primarily surgical.