Vascular manipulations that differed from the standard technique of renal transplantation were required in 40 of 107 human renal transplantations (38%). Double renal arteries were managed successfully by a side-to-side arterioplasty to form a single common lumen in nine instances. Polar infarcts occurred in seven of eight cases requiring ligation of polar arteries. Double renal veins were probably handled by ligating one of the veins because of the extensive intrarenal venous communication. Endarterectomy of the recipient's iliac system was required in ten transplants because of extensive atherosclerosis. It is concluded that the frequency of vascular abnormalities encountered in renal transplantation requires that the transplant surgeon be familiar with a variety of vascular surgical techniques.