UNDER THE caption of "fatal cryptogenic neuropathy," we wish to put on record the clinical and pathologic observations in 3 cases in which the brunt of the disease was sustained by the peripheral nervous system (roots and nerves), though in 2 of the cases there were evidences of lesser involvement of other parts of the neuraxis. Use of the usual prefixes indicative of such higher involvement, to which the suffix "pathy" must needs be added, would lead to a compound and cumbersome title which would not emphasize the major implication of the peripheral nerves. However, we would not give the impression that we are describing a new disease, clinically or pathologically. In the recent neurologic literature there are many well known references to special forms of neuritis or neuropathy the cause of which is unsettled. Thus, one may refer to the group of cases described by Guillain, Barré and Strohl