Eight patients with two or three symptoms of the Klippel-Trénaunay triad were examined. All patients had varices, increased chloride concentration of sweat and, with one exception, hemangiomas. Four patients showed osteohypertrophy and one patient revealed signs of a-v fistulas. Venous outflow impairment as in deep venous occlusion is known to produce osteohypertrophy in children. The authors are of the opinion that a hemangioma actually is a functional a-v fistula. A hemangioma located in the vicinity of an epiphyseal zone may well cause a localized outflow impairment of the veins draining the epiphyseal zone, leading to an increased growth of the bone. Although patients with the Klippel-Trénaunay triad, Parkes-Weber syndrome and agenesis of the deep veins constitute an