In a randomized, double-blind, placebo-controlled, crossover study with two 4-week treatment periods, we investigated the effects of calcium channel blockade with 5 mg slow release oral isradipine on postexercise blood pressure and systemic hemodynamics (echocardiography) in ten hypertensive patients. The results show that the combination of exercise and isradipine treatment exerts additive antihypertensive effects in hypertensive patients after exercise. The antihypertensive effect of prior exercise with placebo was related to a significant fall in total peripheral resistance. After exercise during isradipine treatment, total peripheral resistance was lower than with placebo. Thus, isradipine exerts an additional antihypertensive effect during the postexercise period, which appears to be mediated by a further reduction of total peripheral resistance.