In end-to-side vessel-anastomoses, a side fenestration should be made by a slit incision or partial excision of the vessel wall. However, a slit incision might restrict blood flow across the anastomosis, and a partial vessel wall excision using micro-scissors may be time-consuming and result in irregular edges, which may weaken the vessel wall and cause flow disturbances. We used a biopsy punch for end-to-side anastomosis, and obtained satisfactory results. Between September 2015 and August 2017, 27 end-to-side anastomoses using punch biopsies were performed. Two vessel clamps were applied to the recipient vessel proximal and distal to the point planned for the side anastomosis. The flap side vessel size was measured, and an appropriately sized punch was selected. The clamped recipient vessel was supported by a wooden tongue depressor and the punch was applied to the vessel wall. An end-to-side anastomosis was performed in the usual manner, and immediate patency was tested with a refill test. The vessel patency rate was 96 percent. The mean arteriotomy or venotomy time was 65 s and entire anastomosis procedure time was 1065 s. Both the vessel preparation and the micro-anastomosis procedure times were shorter than those of the conventional procedure group with statistical significance. ( < .05) There was only one case of venous failure by deep vein thrombosis - and it was resolved with thrombectomy and re-anastomosis. Use of a biopsy punch in end-to-side anastomosis can offer a uniform circular edge and reduce operating time.