Exercise renography is essentially a research method to investigate hypertension and has very limited clinical application. Captopril renography has long been used to study renal artery stenosis causing hypertension with good results. The authors describe a patient with a transplanted kidney supplied by reversal of flow via the external iliac artery. A "steal phenomenon" of the kidney related to ambulation was considered likely. Ischemia of the transplanted kidney was revealed by exercise renography, which showed parenchymal trapping of radiotracer as a result of exercise.