Résumé : Among 241 renal transplants with implantation of the ureter into the urinary bladder, the endovesical technique of Politano and Leadbetter (PL) was used in 108 cases and the extravesical technique of Grégoir and Lieh (GrL) was used in 133. Urinary fistulas occurred in 10 patients (9.3%) with the PL technique and in only 1 patient (0.8%) with the GrL technique. The difference was highly significant (p<0.01). Stenosis of the ureter developed in 3 patients (2.8%) following the PL technique and in 9 patients (6.8%) after the GrL technique, an insignificant difference (p>0.10). None of the complications resulted in death or failure of transplantation. It is concluded that the extravesical technique of Grégoir and Lich is the best method of avoiding urinary leakage, which is the most dangerous urologic complication of kidney transplantation. © 1977 Société Internationale de Chirurgie.