Since the renewed interest in keratoacanthoma, for which the credit goes to Rook and Whimster,1 this tumor has not ceased to draw the attention of dermatologists. Onset of keratoacanthoma following the administration of mercurial diuretics,2 mucous membranes as the site of localization3 on the clinical side, and production in certain animals4,5 on the experimental side have been the subjects most recently dealt with in the literature. Recently we have had the opportunity to observe a keratoacanthoma of the benign course in a young patient with xeroderma pigmentosum. Report of a Case The patient, a very intelligent young girl of 13, has been under our regular supervision for the last 2 years. She is the youngest of 3 siblings. The skin of the other 2 sisters are not affected. Their parents are not blood related. Strong erythema of the face appeared during one of her first exposures