The article deals with the substantiation, techniques, and possibilities of treating long-term spasm of the cerebral vessels in patients with ruptured arterial aneurysms by means of an intravascular intervention, dilatation of the spastic vessels with a balloon catheter. Thirty-three large cerebral vessels (internal carotid arteries, the basilar artery, and their branches) were dilated in 13 patients. Vasodilation could not be accomplished in only one patient in the group discussed. The increase in the vascular lumen proved to be stable, and the functional state of the brain in patients subjected to surgical treatment of spasm of the cerebral vessels improved. The authors discuss the indications for and the performance of the suggested intervention, the time of its performance, the boundaries of vasodilatation, and possible mechanisms of circulation improvement in the brain stem. The duration of the effect of dilatation of the spastic cerebral vessels is, according to the authors, the most complex problem.