Purpose: We compared captopril renal scintigraphic criteria for the diagnosis of renovascular hypertension by unilateral renal artery stenosis. Materials and Methods: The study group consisted of 24 patients (m/f =16/8, age: 39±18 years) with unilateral renal artery stenosis who underwent renal artery revascularization and captopril renal scintigraphy with ^99mTc-diethylenetriaminepentaacetic acid between May 1995 and April 2004. The blood pressure response was classified as cure/improvement or failure. We evaluated captopril-induced changes in relative function (BCfun) and renogram grade (0 to 5: 0 = normal, and 5 = renal failure pattern without measurable uptake) (CBren) and the difference of renograms between the normal and stenotic kidney on captopril scan (CNren). Results: Eight of 24 patients were cured and 11 improved and 5 patients were classified as failed revascularization. Significant predictors of a cure or improvement of blood pressure were younger age, stenosis by fibromuscular dysplasia or arteritis, BCfun, CBren and CNren. Areas under the receiver operating characteristic curve of age, BCfun, CBren and CNren were not significantly different. Positive and negative predictive values of predictors were 100% and 42% (age ≤ 38); 92% and 50% (BCfun ≥ 1%); 92% and 75% (CBren ≥ 1), and 90% and 60% (CNren ≥ 1), respectively. Conclusion: Captopril induced changes in renal function and renogram can reliably predict hypertension response to revascularization. Renogram pattern on captopril scan can diagnose renovascular hypertension without baseline data in patients with unilateral renal artery stenosis.(Korean J Nucl Med 38(6):498-505, 2004)