Hennekam syndrome is a rare, recently described genetic disorder in which facial anomalies and mental retardation accompany congenital lymphedema and intestinal lymphangiectasia. Several other somatic abnormalities have variously been described, as have milder degrees of lymphatic dysfunction. The authors herein describe a case of Hennekam syndrome in which the diagnostic difficulties were partially overcome by the judicious use of radionuclide scintigraphy to verify the lymphedematous component of the patient's presentation.