The clinical course of an adolescent with reflex sympathetic dystrophy of the foot is presented. The potential problems of establishing objective diagnostic criteria for reflex sympathetic dystrophy are related to the dynamic nature of the disorder. Serial radiographic studies, radionuclide scans, and quantitative densitometric measurements may be useful in combination; isolated cold stress testing and laser Doppler fluxmetry are useful in assessing thermoregulation and vasomotor instability. A regimen of amitriptyline and phenytoin plus physical therapy with stress loading was useful in this patient, but in many patients the course is progressive, leading to chronic pain and debilitation.