OBJECTIVE To compare the efficacy and safety of iv nicardipine with sodium nitroprusside in the treatment of postoperative hypertension after both cardiac and noncardiac surgery. METHODS Multicenter, prospective, randomized, open-label study. METHODS Six tertiary referral medical centers (recovery rooms and surgical ICUs). METHODS A total of 139 patients with postoperative hypertension: i.v. nicardipine (n = 71), sodium nitroprusside (n = 68). METHODS Administration of i.v. nicardipine or sodium nitroprusside. METHODS Vital signs (BP, heart rate), hemodynamic variables, medication dosage, total number of dose changes, and time to achieve BP control were recorded. RESULTS Both medications were equally effective in reducing BP in both the cardiac and noncardiac surgical groups. Under the conditions of the study, i.v. nicardipine controlled hypertension more rapidly than sodium nitroprusside (i.v. nicardipine 14.0 +/- 1.0 mins and sodium nitroprusside 30.4 +/- 3.5 mins, p = .0029). The total number of dose changes required to achieve therapeutic BP response was significantly less in the i.v. nicardipine-treated patients (i.v. nicardipine 1.5 +/- 0.2 vs. sodium nitroprusside 5.1 +/- 1.4, p < .05). Adverse effects were observed with both drugs (i.v. nicardipine 7% [5/71] and sodium nitroprusside 18% [12/68] [NS]). CONCLUSIONS Intravenous nicardipine is as effective as sodium nitroprusside in the therapy of postoperative hypertension. Specific advantages have been identified. The use of i.v. nicardipine should be considered in the therapy of postoperative hypertension.