Saphenous vein interposition grafts of varying lengths have been used in 25 extracranial-intracranial bypasses since 1974. Indications for operation included transient ischemic episodes (13 cases), prophylactic augmentation of middle cerebral artery (MCA) collateral flow prior to surgical treatment of intracranial aneurysm (four), and traumatic occlusion of cervical or intracranial internal carotid arteries (eight). Vein grafts to cortical branches of MCA originated from superficial temporal or occipital arteries in ten cases, common or external carotid arteries in ten, and subclavian or innominate vessels in five. Twenty-one patients have been followed up for a minimum of 12 months. Immediate patency rate was 84%; one late graft occlusion decreased overall patency to 80%. There was one operative mortality. Early technical problems, including donor-recipient size disparity, anastomotic distortion, and inappropriate graft routing, have been overcome by the use of 2-mm veins, the avoidance of hydrostatic dilation, and the construction of retroauricular tunnels. It is reasonable to assume that long-term patency of these reconstructions will parallel that of extracranial-intracranial bypasses using autologous arteries.