We describe methods for using ameroid constrictors to develop renin-dependent hypertension in dogs. A vascular-access-port was implanted in each dog and mean arterial blood pressure was monitored. Via a small flank incision, an ameroid constrictor was placed on the left renal artery and mean arterial blood pressure, plasma renin activity, and the response to angiotensin-converting enzyme inhibition measured during the subsequent 4 weeks. Placement of the constrictor on the left renal artery resulted in a significant increase in plasma renin activity which was accompanied by a significant hypertension (blood pressure greater than 140 mmHg). The greatest increase in plasma renin activity and blood pressure occurred at week two which coincided with the greatest response to angiotensin-converting enzyme inhibition, when mean arterial blood pressure decreased more than 30 mmHg after administration of either captopril or enalapril (1 mg/kg, i.v.). The results of this study indicate that ameroid constrictors provide a reliable method for establishing renin-dependent hypertension in dogs.