Aortic stiffness increases with advancing age and is associated with the age-related decline in exercise capacity in healthy persons. Previous studies have suggested that aortic compliance is reduced in heart failure (HF). Older persons with systolic HF can have particularly severe exercise intolerance. However, the relation between increased aortic stiffness and exercise intolerance in elderly patients with systolic HF has not been examined. Therefore, aortic distensibility of the proximal ascending aorta (assessed by magnetic resonance imaging) and exercise tolerance (assessed by maximal exercise ergometry with expired gas analysis) was measured in 28 subjects (10 healthy subjects aged 20 to 30 years, 10 healthy subjects aged ≥60 years, and 8 subjects aged ≥60 years with systolic HF). Compared with healthy older subjects, patients with systolic HF had markedly decreased distensibility of the proximal aorta (0.5 ± 0.4 vs 2.2 ± 1.2 10⁻³ mm Hg⁻¹, p <0.002), decreased peak exercise volume of oxygen consumption (VO₂) (858 ± 248 vs 1,436 ± 344 ml/min, p <0.001), and increased aortic wall thickness (3.6 ± 0.7 vs 2.9 ± 0.4 mm, p <0.04). Aortic distensibility was significantly correlated with peak VO₂ (r = 0.80, p <0.0001) and remained so even after being adjusted for age and left ventricular (LV) ejection fraction. These data suggest that decreased aortic distensibility may contribute to exercise intolerance in older patients with HF due to LV systolic dysfunction.