Background: Cardiologists from all around the world are now debating the subject ejection fraction is still preserved in heart failure (HFpEF). HFpEF has a wide range of composite etiology and pathophysiologic processes. While the main worry is diastolic dysfunction, which includes aberrant passive stiffness that is increased while actively relaxing. Objective: The present study aimed to establish the connection between 24-hour Blood Pressure Variability and tolerance patients with heart failure whose ejection fraction has remained stable should exercise. Patients and methods: A case control study was conducted on 120 patients with typical symptoms and signs of heart failure, whose left ventricular ejection fraction (LVEF) ≥50% at Zagazig University Hospital from February 2020 to January 2021. The study recruited 80 patients with HFpEF and 40 control subjects. The search strategy targeted subjects with normal echocardiogram. Results: HFpEF patients with reduced exercise capacity had higher BPV index values compared with those with good exercise tolerance. Additionally, fractional shortening time (6 Minute Walking Test) was negatively correlated with LAVI, E/e' ratio and left ventricular desynchrony BPV index was very excellent independent predictor of decreased exercise capacity in addition to left ventricular desynchrony. BPV index ≥10.65 mmHg and Ts-SD ≥31.5 were the ideal cut-off values for identifying patients with impaired exercise ability with HFpEF. Conclusion: Use of BPV along with comprehensive echocardiographic assessment including LAVI and e` as important and feasible tool in diagnosis and people with HFpEFs prognosis.