Technetium-99m-ethylenedicysteine (99mTc-EC) captopril scintigraphy performed in a patient with severe hypertension revealed increased parenchymal retention in the left kidney, suggesting renal artery stenosis. After angiographic confirmation of renal artery stenosis, percutaneous transluminal angioplasty (PTA) was performed on the left renal artery. Captopril scintigraphy after PTA showed normal findings with no evidence of parenchymal retention, consistent with reversal to normal kidney functions. In light of this case of renal artery stenosis, it was concluded that 99mTc-EC can be used successfully as a potential renal agent in the diagnosis and follow-up of renovascular hypertension.