Psoriasis of the lips was observed in a 54-year-old female who had suffered from psoriasis vulgaris for 18 years. The psoriasis of the lips was preceded by protrusion of the upper teeth. Topical corticosteroid and later 5-fluorouracil treatment were ineffective. The disease recurred even after replacement of the vermilion by plain mucosa. The disease was successfully treated by replacement of the protruding teeth by a nonirritating prosthesis.