A review of the clinical, and especially the neuropathologic, data on the heredo-familial form of spastic paraparesis or paraplegia was presented in 1952.1In this report there were included a pedigree and clinical studies of some of the members of a family designated as Family Ze. Since that time, one of us (G. A. S.) has had the opportunity of examining a younger member of this family who has recently developed the disease. Clinical studies of another family have been acquired. Finally, we obtained the central nervous system of one of the afflicted members of the Ze family for pathologic study. We felt that the presentation of all this newly acquired material would significantly extend the earlier report. CLINICAL AND PATHOLOGIC REPORTS IN THE LITERATURE The reports of Rhein,2Paskind and Stone,3Price,4Bell and Carmichael,5and Schwarz1gathered the numerous clinical and pathologic