41 patients with ruptured intracranial aneurysms were all submitted to an early operation, (within 3 days from SAH), and evaluated with regard to the results of treatment. In this group, vasospasm has influenced the outcome more than other causes, accounting for 58% of morbidity and 64% of mortality. On the basis of our experience with 380 patients suffering from SAH and all submitted to a CT scan, the presence of consistent intracisternal blood in the CT scan at admission has shown to be the main risk factor resulting in vasospasm. Therefore, the group with early surgery has been compared, on the basis of the CT scan picture, to a group of 76 patients in which surgery had been delayed at least 10 days after SAH. Whilst the incidence of vasospasm has been very similar in the groups compared, the incidence of neurological deterioration brought about by spasm has been higher in patients waiting for surgery (55%, against 36% in the group with early surgery). Avoidance of clinical deterioration has not been always possible with early surgery, even after careful cleansing of the cisterns from clots, as was shown by 2 of our cases. It is concluded that vasospasm does not seem to influence the outcome of early surgery to a greater extent than it would during the natural course of subarachnoid haemorrhage.