Among 110 patients who underwent corrective surgery for unilateral renovascular hypertension, we found that a preoperative of hypertension was a highly important predictor of postoperative achievement of normotension. Those with less than a 5-year history of hypertension experienced 78% incidence of successful outcome, compared to such a salutary frequency of only 25% in patients with longer hypertension duration. Although the best renal vein renin (RVR) boundary ratio (1.4) was less predictive of overall surgical success in the population studied, the prognostic value of this test improved considerably when analysis of RVR ratio results were confined to patients not receiving renin-suppressing agents during RVR sampling and who had technically satisfactory operations. Highest surgical benefit rate occurred in the group of patient with both short duration of hypertension and high RVR ratio. Conversely, patients with long hypertension duration and low RVR ratio exhibited lowest surgical success frequency. Therefore, duration of hypertension is hereby shown to be an important factor in the preoperative evaluation of appropriate management of patients with renovascular hypertension.