Object. The aim of this study was to assess the incidence and outcome of procedure-related rupture of intracranial aneurysms in patients treated with Guglielmi detachable coils (GDCs) and to identify risk factors for this complication. Methods. Procedure-related rupture occurred in seven of 264 treated aneurysms in 239 consecutive patients. Aneurysm size, history of previous subarachnoid hemorrhage (SAH) caused by the treated aneurysm, timing of treatment after SAH, and the use of a temporary occlusion balloon in the seven procedures in which rupture occurred were compared with the remaining 257 procedures, and these findings were correlated with data from 13 studies in the literature, in which results of 2030 aneurysm treatments were reported. Conclusions. Procedure-related rupture of intracranial aneurysms during GDC treatment occurs in 2.5% of cases and is responsible for 1% of treatment-related deaths. Risk factors are as follows: small aneurysm size, previous SAH, and probably the use of a temporary occlusion balloon.