We investigated clinical manifestations in 124 patients with a possible Turcot's syndrome whose data were taken from documented cases. The cases were subclassified mainly on the bases of the type of familial occurrence and listed in five Tables. We searched for differences in colonic manifestation, histologic type of glioma, mode of inheritance, frequency of parental consanguinity, skin lesions and other accompanying lesions among these five groups. The differences of these clinical findings suggested that glioma-polyposis syndrome should be classified as follows; (1) cases of Turcot's syndrome who had characteristic colonic and brain manifestations, (2) cases of FAP associated with glioma, (3) suspicious cases of glioma-polyposis, and (4) cases other than glioma-polyposis syndrome.