Familial spastic paralysis is characterized clinically by the hereditary or familial occurrence of spastic paralysis, which is the cardinal and constant symptom of the disease; it is sometimes the only symptom. In a disease of this nature, however, it is hardly to be expected that the lesions should be confined exclusively to the pyramidal tracts; other parts may be and often are involved; accordingly, with the spastic paralysis there have been reported other symptoms, such as defective mental development, convulsions, optic atrophy, nystagmus, extra-ocular palsies, tremors, speech disturbances—especially scanning speech—and muscular atrophies. The disorder is rare; our purpose is to report the occurrence of the disease in three members of a family seen recently in the neurologic clinic of Northwestern University Medical School, to review the literature and to describe in detail the pathologic findings in the oldest of the three patients. REPORT OF CASES Family History. —The paternal grandfather,