An attempt has been made to enumerate or describe briefly the various clinical manifestations which may be associated with congenital neurofibromatosis. In some instances the direct relationship can be proved, but in the majority of cases this has to be assumed. The frequency with which these various questionable manifestations are associated with unmistakable signs of neurofibromatosis, however, and the tissue characteristics which are found so commonly in all cases of soft-tissue hypertrophy, represent strong presumptive evidence that all may arise from a common etiology,—a primary developmental defect of the nervous system.