The Klippel-Trenaunay-Weber syndrome is a rare disorder characterized by congenital vascular hamartomas, limb hypertrophy, cutaneous manifestations, lymphangiomas and atresia of lymph vessels with non-pitting edema. A three-year-old boy was referred to our clinic for progressive hypertrophy of leg and feet with 32-month history. We diagnosed Klippel-Trenaunay-Weber syndrome, and determined vesicoureteral reflux in our patient. To our knowledge, hydronephrosis and vesicoureteral reflux have not been described previously in the KTWS.