Doppler indexes were measured in 14 renal arteries in 13 patients before and after percutaneous transluminal angioplasty to determine if changes in these parameters occurred after the procedure. Angioplasty was technically and clinically successful in 12 cases, and adequate Doppler signals were obtained from 13 of 14 arteries. The pulsatility index, resistive index, and acceleration of the distal main renal artery Doppler waveform increased significantly after angioplasty, while the time to systolic peak and the renal-aortic ratio remained unchanged. The former may be useful noninvasive indexes to screen patients for restenosis of the renal artery before it becomes clinically evident. A long-term follow-up study is needed to test this hypothesis.