The treatment of cerebral aneurysms is changing from surgical clipping to endovascular coiling (EVC) in many neurovascular centres. The aim of this study was to evaluate the technical results and clinical outcome at 6 months in a consecutive series of subarachnoid hemorrhage (SAH) patients treated with EVC, in a situation when the EVC had been established very rapidly as the first line of treatment at a neurovascular centre. The patient material comprised 239 SAH patients (155 women and 84 men, mean age 55 years, age range 16-81) allocated to EVC as the first line of treatment in the acute stage (within 3 weeks of rupture) between September 1996 and December 2000. Clinical grade on admission was Hunt & Hess (H&H) I and II in 42%, H&H III in 25% and H&H grade IV and V in 33% of the patients. The aneurysm was located in the anterior circulation in 82% of the cases. EVC was performed on days 0-3 in 77% of the cases. EVC of the target aneurysm was able to be completed in 222 patients (93%). Complete occlusion was achieved in 126 patients (53%). Procedural complications occurred in 39 patients (16%). Favourable clinical outcome was observed in 57%, severe disability in 28% and poor outcome in 14% of the patients. Favourable outcome was achieved in 77% of H&H I and II patients and in 43% of H&H III-V patients. The multivariate logistic regression analysis revealed that younger age, good neurological grade on admission, absence of intracerebral hematoma and intraventricular hematoma respectively, ICA-PcomA aneurysm location, later treatment and absence of complications were significant predictors of favourable outcome. After interventional training and installation of the X-ray system, the introduction and establishment of EVC at a neurovascular unit can be done in a short period of time and with favourable results. Future studies must concentrate on identifying factors of importance for the choice of interventional or surgical therapy. The results of this study indicate that endovascular therapy may be particularly beneficial in poor-grade patients and in patients with aneurysms in the ICA-PcomA territory.