Kidney transplants from infant donors are associated in the literature with poor results as regards both functionality and the survival of the transplant. Hence the increasing frequency, for kidneys obtained from donors under 5 years of age, of a surgical technique defined as "en bloc", involving the transplant of both kidneys into a single receiver and using the donor aorta and vena cava for vascular anastomosis. This technique seems to provide results comparable with those obtained using adult organs. Ultrasound and Doppler investigations are routinely performed in patients undergoing such a transplant. This study presents ultrasound and Doppler images of "en bloc" transplants, with particular reference to one case of pseudoaneurysm of the donor aorta and one of stenosis of the renal artery, revealed by Echo-Color-Doppler. The importance of ultrasound in this kind of transplant is emphasized, as it enables post-operative monitoring of the physiological growth in volume of the two transplanted infant kidneys.