Intraoperative angiography evaluation of the clippings of cerebral aneurysms was investigated in a series of 38 consecutive patients with unruptured cerebral aneurysms to determine any favorable impact on the outcome. Unexpected findings including major arterial occlusion or residual aneurysm were identified. Specific variables such as the size and site of aneurysm were analyzed to determine the impact on clinical outcome and the incidence of clip modification. There were 11 large and 27 small aneurysms in this series. Mortality and permanent morbidity after microsurgical clipping were 0.0% and 2.6%, respectively. Unexpected angiographic findings necessitating clip repositioning consisted of residual aneurysm in two cases and distal branch occlusion or parent vessel stenosis in four. The need for clip modification was significantly higher for large than for small aneurysms (p = 0.007), and the rate of clip adjustment increased with increasing aneurysm size (p = 0.008). Intraoperative assessment prior to wound closure allows for the recognition and correction of defects and decreases the risk of postoperative complications. Intraoperative angiography may become important in the microsurgical clipping of unruptured cerebral aneurysms, especially large aneurysms.