The course of vasospasm following subarachnoid haemorrhage in rats was studied using vertebrobasilar angiography. Wistar and Sprague Dawley rats were compared with respect to vasospastic response after bleeding. A more pronounced vasospasm was found in Sprague Dawley rats. In order to avoid a possible toxic effect on the contrast medium, only one angiogram per animal was initially performed. However, a comparison with the results obtained in a separate series of non-challenged animals demonstrated a difficulty due to high variability in basilar artery size in the latter group. Therefore, vasospasm can be more readily shown if multiple angiograms are used in the same animal so that the vasospasm can be expressed as a percentage of the initial diameter of the basilar artery. It was found that multiple angiograms are well tolerated when non-ionic contrast media are used.