Disturbances of the sympathetic impulse in the extremities are still too little understood. From time to time reports of conditions suggesting dysfunction of the sympathetic system affecting the blood supply reach the literature. The clinical expressions of sympathetic dysfunction in any group of cases are apt to be variable and difficult to correlate. Among the array of conditions in which hyperactivity of the sympathetic system can be descried, traumatic vasospasm may be picked out as a more or less definite entity. Individual instances of traumatic vasospasm are so different from each other in their details that the total clinical picture is not easy to visualize. They have two factors in common: (1) trauma, usually received at some time considerably earlier than the patient is seen, and (2) evidence of vasospasm. Confusion arises because one often sees additional disturbances of somatic sensory and motor function as well as so-called trophic changes.