A case of basal cell epithelioma of a pilonidal sinus is presented and is the third one documented to our knowledge. Sixteen pilonidal squamous cell carcinomas, two adenocarcinomas, one mixed basosquamous malignancy, and one unclassified case have been gathered from the literature. Of these, 17 occurred in men and only three in women. The pilonidal malignancies are tabulated. Recent observers favor the acquired rather than the congenital nature of the pilonidal sinus. In view of the possibility of neoplasia developing in pilonidal sinus, postanal prophylaxis is advised, and careful clinical and microscopic evaluation of all sacrococcygeal pilonidal sinuses is stressed.