The incidence of intraoperative aneurysm rupture (IAR) was studied in a consecutive personal series of 222 patients operated on for a ruptured intracranial aneurysm. In 77 patients subjected to early surgery (operation within 72 h after rupture) IAR was 40.2% and in 145 patients with surgery after 72 h IAR was 20.7%. The mortality and severe morbidity (GOS grade 4 and 5) were 2.6% in the early surgery group, 7.6% in the late surgery group, and 5.85% in the total series despite the fact that there was a significantly higher incidence of IAR in the early surgery group. Aneurysms arising from the anterior cerebral artery (ACA) or anterior communicating artery (ACoA) appeared more prone to IAR--36.9 versus 18.6 and 23.2%--than aneurysms at other locations. There was no correlation between incidence of IAR and preoperative Hunt and Hess grade [8]. IAR affected final outcome only when it occurred prematurely during introduction of anesthesia or during opening of the dura. In conclusion, although IAR occurs more frequently when surgery is undertaken in the early stage after rupture, this complication is in experienced hands not necessarily associated with an increased risk for an unfavorable outcome.