In 216 consecutive patients investigated for subarachnoid haemorrhage, 44 (20.3%) of cerebral angiograms were either normal or equivocal for the presence of aneurysm. Arteriography was repeated in 30 patients and an aneurysm was demonstrated in 10 cases. Repeat arteriography is recommended in proven subarachnoid haemorrhage even when the initial study is normal, and in this study achieved a reduction in overall negative rate to 15.6%.