• Malignant gliomas of the optic path-ways are uncommon in adults and are rarely diagnosed in life. In three cases of such tumors, the diagnosis was not suspected during life. Neuropathological examination showed involvement of the optic nerves, chiasm, and tracts with extensive involvement of contiguous structures in all of the cases. In view of the consistent clinical features, it is stressed that in adults with progressive visual failure, malignant gliomas of the optic path-ways be included in the differential diagnosis.