Some aspects of the pathogenesis of acute spinal epidural haematoma are still obscure. However, if the possibility of an iatrogenic lesion is excluded, it must be assumed that there is a congenital or acquired vascular lesion, or else a haemorrhagic diathesis, with minimal trauma or repeated effort acting as a trigger factor. In the vast majority of cases, the syndrome of medullary of cauda equina compression by an acute epidural haematoma has a sudden onset in apparently healthy individuals after a normal amount of effort. In such circumstances the search for predisposing causes can only be speculative. In the present case, there were severe arthrosic changes, whose effect on the dural sac was demonstrable myelographically, but which was previously asymptomatic. Treatment is exclusively surgical. It is effective the earlier it is undertaken. The need for emergency surgery is clearly demonstrated by its inefficacy if delayed for twenty-four hours after the onset of the symptoms.