The current European and US hypertension guidelines widely recommend regular physical activity. However, it remains elusive whether exercise can also reduce recalcitrant hypertension. The current randomized controlled trial examined the cardiovascular effects of aerobic exercise on recalcitrant hypertension. Intractable hypertension was defined as blood pressure ≥140/90 mm Hg even after use of 3 antihypertensive medications or requiring 4 or more antihypertensive medications to control blood pressure. 50 subjects with intractable hypertension were randomly assigned to participate or not participate in a treadmill exercise program (target lactate, 2.0 ± 0.5 mmol/L) for 8 to 12 weeks with 24-hour blood pressure monitoring. Arterial compliance and cardiac index were measured using pulse wave analysis. The training program was well tolerated by all patients. Exercise significantly reduced daytime ambulatory systolic and diastolic blood pressures by 6±12 mmHg and 3±7 mmHg, respectively (each P=0.03). Routine exercise reduced blood pressure during activity and increased physical function as assessed by maximal oxygen uptake and lactate profile. Arterial compliance and cardiac index remained unchanged. Physical exercise was able to reduce blood pressure in subjects with a low response to medication. It should be included in the treatment of recalcitrant hypertension.