Advances in renal angiography and revascularization techniques have renewed interest in developing a better noninvasive screening test for identifying patients with potentially correctable renovascular hypertension. Captopril renography is a promising diagnostic tool in the evaluation of the hypertensive patient. This review highlights the important pathophysiological changes in renal hemodynamics and humoral response attributable to significant renal artery stenosis, and underscores the dramatic effects of angiotensin-converting enzyme inhibition on the renovascular bed. The review also summarizes the available clinical information in captopril renography, and presents consensus recommendations on appropriate patient selection, radionuclide(s) of choice, and suggested diagnostic criteria.