Fifty four patients (33 male and 21 female, mean age 47) with spontaneous aneurysmal subarachnoid hemorrhages have been tested by repeated TCD: 25 of them were systematically administered intravenous Nimodipine when admitted at hospital, the 29 others constituted a reference group. There was no statistically significant difference between the two groups of patients for age, sex, initial clinical status, importance of bleeding at CT scan, localization of aneurysm or existence of an angiospasm, whether clinically symptomatic or not. In 72% of the cases, TCD allowed to prove the existence of an angiospasm when higher flow velocity was registered in cranial basal arteries. There was no significant difference between the two groups. The final clinical status of the patients seemed to be more favourable in the treated group. Yet it did not appear to be directly linked to the existence of a spasm or not. This argued in favour of a non-univocal mechanism of action of Nimodipine.