Patients with chronic snuff-induced keratosis associated with mucosal ulcerations were treated with topically applied vitamin A acid. In each case, after a marked, local inflammatory response initially, topical vitamin A acid showed a definite beneficial effect in promoting healing and involution of the precancerous snuff-induced leukoplakic keratosis. In one patient there was distinct involution of the oral lesions with complete healing and restoration of a normal-appearing mucosa within five weeks after beginning of treatment. In four patients there was healing of superficial ulcerations and regression in the size of the luekoplakic lesions.