Klippel Trenaunay-Weber syndrome is a complex developmental disorder characterized by a triad of cutaneous haemangioma, varicosities of the body, and unilateral limb hypertrophy. We describe the prenatal diagnosis of Klippel-Trenaunay-Weber syndrome at 15 weeks' gestation using the surface rendering technique of three-dimensional ultrasound. The vivid three-dimensional images of the affected fetus are invaluable in prenatal diagnosis and parental counselling.