The ostium of the recipient artery and the orifice of the donor artery must be clearly visualized for the establishment of microvascular anastomosis. Specially designed colored flexible cylindrical or T-shaped silicone rubber stents were made in various sizes (400 or 500 microns diameter and 5 mm length) and applied to bypass surgery in patients with occlusive cerebrovascular disease such as moyamoya disease and internal carotid artery occlusion. The colored flexible stents facilitated confirmation of the ostium of the artery even in patients with moyamoya disease and allowed precise microvascular anastomosis without problems caused by the stent.