OBJECTIVE To improve arterial anastomosis method for rat renal transplantation. METHODS Renal transplantations were performed on 72 wistar rats. The donor superior mesenteric artery was end-to-end anastomosed to the recipient left renal artery by using of sleeve anastomosis technique. The external diameters of the vessels anastomosed were 0.60 +/- 0.05 mm (left renal artery) or 0.80 +/- 0.07 mm (superior mesenteric artery). The procedure consisted of a guiding suture and two fixing sutures. The guiding suture was used to "telescope" the recipient left renal artery into the donor superior mesenteric artery about 2 millimetre. Two fixing sutures were applied 180 degrees apart from each other and tied. Three sutures passed through all layers of the donor superior mesenteric artery and constricted the vessel lumen, but only penetrated the adventitia of the recipient left renal artery. RESULTS The time for arterial anastomoses was approximately 6 to 8 minutes. The renal grafts perfused very well after the recipient left renal artery clamp was removed. Complications included anastomotic hemorrhage (1 case) and thrombosis (1 case). Histologic examination of 34 grafts at different postoperative time ranging from 6 to 30 days revealed that renal artery was fully patent, with no evidence of ischemic injury. CONCLUSIONS The modified arterial sleeve anastomosis technique is simple and feasible regardless of experimental condition and can be easily performed.