Rat kidney transplantation is a frequently used model in transplantation research and experimental microsurgery. This model has been used in studies which cover most aspects of transplantation biology. Thus in many laboratories attempts was made to improve this experimental model. However, the available techniques mostly are time consuming and the methods of urinary tract reconstruction are unsatisfactory because of numerous complications. Therefore, a detailed description of the orthotopic kidney transplantation in the rat, using end-to-end anastomosis of the kidney vessels and non-splinted end-to-end anastomosis of the ureter with simultaneous bilateral nephrectomy is presented. This technique based on preliminary experiences with 34 rat kidney transplants has produced success in 32 transplants.