On the basis of a personal series of 372 cases of renal transplantation performed in children, half of whom presented congenital urinary tract malformations, the authors report 110 complications (29.6%). The most frequent complications were urological (14.2%), consisting essentially of fistulae (8.9%) and stenoses (3%). These were followed by vascular complications (6.4%) generally in the form of stenoses (4.8%) and rarely thromboses (1.1%). The authors also report the various local complications which were infectious (wall abscess, suppuration of the renal compartment), haemorrhagic (haematomas) or stones (stones forming on non-resorbable sutures) as well as 5 cases of lymphocele. The prophylaxis of these complications depends on the care taken in collection of the graft (en bloc removal of both kidneys), the restoration of the continuity of the urinary tract (as much as possible Lich-Gregoire extravesical uretero-vesical reimplantation), the vascular anastomoses (vascular dissection limited to a strict minimum), the choice of suture material (resorbable synthetic suture material) and the prevention of infection by systematic pre-, intra- and post-operative antibiotic therapy.