Application of endovascular surgery for very small aneurysms is controversial because of technical difficulties and high complication rates. The aim in the present study was to assess treatment results in a series of such lesions at one institution. Since 1997, endovascular surgery has been advocated for very small ruptured aneurysms (< 3 mm in maximum diameter) that fulfill the criterion of a fundus/neck ratio greater than 1.5. Twenty-one patients were treated, for whom the World Federation of Neurosurgical Societies classification before treatment was Grade I in 10, Grade II in two, Grade III in two, Grade IV in five, and Grade V in two. The aneurysm location was the internal carotid artery in four, the anterior communicating artery in 11, the middle cerebral artery in one, and the vertebrobasilar system in five. In all patients, endovascular surgery was performed using Guglielmi detachable coils after induction of general anesthesia. Initially, the presumed volume of the lesions was calculated for each aneurysm. Thereafter, the appropriate coil length was decided according to the volume embolization ratio, as 30 to 40%. In all attempts to obliterate aneurysms a single coil was used. All aneurysms were completely obliterated as confirmed by postembolization angiography, without procedure-related complications. During the follow-up period only one patient needed additional coil embolization for a growing aneurysm. Final outcomes were good recovery in 15 patients, moderate disability in five, and severe disability in one. Appropriate selection of patients and coils, and use of sophisticated techniques allow a good outcome for patients with very small aneurysms.