Stroke from surgically inaccessible intracranial atherostenosis remains a formidable clinical challenge. While antithrombotic or antiplatelet therapy may prevent distal embolism, there is no effective program for plaque stabilization preventing progression of atherosclerotic stenosis. In patients with isolated circulations (single vertebral with absent posterior communicating arteries, single carotid with contralateral internal carotid artery occlusion, or single carotid with an absent anterior communicating artery), occlusion of the stenotic vessel may produce a low flow-mediated stroke. Fifteen patients with atherosclerotic intracranial stenoses were treated by balloon angioplasty after medical therapy with warfarin failed. Treated territories included the distal internal carotid, proximal middle cerebral, distal vertebral, and basilar arteries. Dilation was successful in all vessels, with residual stenoses averaging less than 30%. Two complications included one paramedian pontine stroke and a single vessel rupture that proved fatal. There was no recurrence of transient ischemic attacks and no restenosis at the angioplasty site over a follow-up period of more than 24 months. In this small series, balloon angioplasty of intracranial vessels provided a therapeutic option for secondary stroke prevention in highly selected patients. Further studies will be necessary to establish the efficacy and safety of endovascular treatment in larger series.