In a randomized double-blind, placebo-controlled, crossover study of isradipine (5 mg twice daily), effects on peripheral hemodynamic reflex responses were studied in nine patients (mean age 48 years) at baseline and after six weeks of active treatment. Assessments included vital signs, resting blood flow in the calf and finger (using an electrocardiograph-triggered venous occlusion plethysmograph), reflex responses during isometric exercise and cold pressor resistance, and venous capacitance in the forearm and calf. Isradipine lowered systolic and diastolic blood pressure as well as mean arterial pressure in patients with mild-to-moderate essential hypertension without reflex tachycardia or venoconstriction. All of the reflex responses studied were attenuated. It is concluded that vasodilatation of the peripheral circulation induced by isradipine contributes partially to the blood pressure-lowering effect. Am J Hypertens 1991;4:194S-196S.