A case of severe head injury with a period of unconsciousness of three days' duration and signs of neurological damage is reported in which, after careful consideration, E.C.T. was given—more than seven months after the original injury—for persistent, intractable and deepening stupor. The symptomatic response was good and was maintained during a period of follow-up of five-and-a-half years since discharge from hospital. Patient made a good working adjustment but some intellectual impairment remained. It is not concluded that E.C.T. should be given in cases of post-traumatic stupor in general, but merely that it was justified by the specific problem posed in this case. The incidence of post-traumatic psychosis is briefly discussed, and reference is made to the possible mode of action of E.C.T. and the absence of obvious deterioration due directly to the latter.