A rare case of Turcot's syndrome is reported in a long-time survivor of glioblastoma multiforme. The patient was treated for his tumor in 1976 with macroscopically complete surgical resection and radiotherapy consisting of 60 Gy to the tumor bed and 40 Gy to the whole brain. Five years later, in 1981, he developed adenocarcinoma of the colon Dukes Stage B which was successfully treated at another hospital by surgery alone. In 1990, he presented with multiple colon polyps and adenocarcinoma Dukes Stage A. For more than 15 years, the patient has been afflicted with cystic and conglobate acne. Possible mechanisms and treatment with 13-cis retinoic acid are discussed.