After a brief statement regarding the volume of cases of cerebrovascular accident occurring in the population an outline of the methods of investigation for suspected cases of ruptured aneurysm was given, stress being laid upon the need for carotid compression on the neck as a preliminary to angiography.The desirability of working out the symptomatology of ruptured aneurysms according to the point of origin was mentioned and the difficulties of lateralising the aneurysms on clinical signs emphasised. A short description of the surgical treatment according to the site of the aneurysm was given and reference made to the experimental programme in progress designed to establish the natural death rate for ruptured aneurysm under conservative treatment.