1. Much attention has been given to the effects of various classes of antihypertensive drugs on blood pressure and haemodynamics. The effects of a single bout of exercise on post-exercise blood pressure have also been studied by several investigators. However, the combined effects of prior exercise and antihypertensive medication has drawn less attention. 2. We examined the separate and combined effects of a single bout of exercise and of angiotensin converting enzyme (ACE) inhibition with a new ACE inhibitor (fosinopril, 20 mg day(-1)) on post-exercise blood pressure and systemic and regional haemodynamics. Ten patients with mild-to-moderate hypertension were studied with a double-blind, randomized crossover, placebo- and rest period-controlled study design. 3. At rest, mean arterial pressure (MAP, -10 +/- 2 mm Hg), total peripheral resistance (TPR, -11 +/- 5%) and forearm vascular resistance (FVR, -17 +/- 8%) were significantly (P < 0.05) reduced during ACE inhibition as compared with the placebo phase. 4. During the placebo phase, MAP (-3 +/- 1 mm Hg), TPR (-10 +/- 4%) and FVR (-9 +/- 4%) were lower after exercise as compared with the control rest period. 5. During ACE inhibition, MAP (-3 +/- 1 mm Hg) and TPR (-8 +/- 4%) were lower, but FVR (+32 +/- 15%) was increased after exercise as compared with the control rest period. 6. Thus, blood pressure and TPR decreased similarly after exercise during the placebo phase and during ACE inhibition. However, differences in post-exercise forearm haemodynamics during the placebo phase and during ACE inhibition indicate that underlying regional haemodynamics are modified.