An end-to-side anastomosis is often a necessity in replantation surgery. This study examines the effects of elliptical versus slit arteriotomy and the angle of anastomosis on vessel patency and aneurysm formation. Forty male rats were divided into four groups of ten rats each. The right and left common iliac arteries were selected as a model. The results showed no significant statistical difference in patency rates among our four experimental groups. The end-to-side anastomotic technique of choice uses the elliptical arteriotomy placed at a 90 degrees angle. It provides good visualization and easy suture placement.