A prospective randomized double blind study was conducted in 70 patients suffering from subarachnoid haemorrhage, due to aneurysm rupture, to determine if the use of nimodipine reduces the severity of ischaemic deficits secondary to vasospasm. At the end of the study, two patients had severe deficit or died in the treated group, while 10 had a bad outcome in the placebo group. Angiographic vasospasm was not significantly different in its frequency or its severity between the two groups. However, the association of extensive and diffuse vasospasm was less frequent in the nimodipine group. This study confirms the effectiveness of Nimodipine in reducing the occurrence of neurological deficit due to vasospasm, even if this action is not observed in all cases.