Background: Metabolic syndrome(MS) is associated with increased LV mass and diastolic dysfunction. However, the effect of MS on LV systolic function at rest and during exercise is still controversial. Therefore, we sought to determine that MS would be associated with decrease in longitudinal contractile reserve during exercise utilizing relatively load independent Doppler tissue echocardiography. Methods: A total of 112 patients with hypertension who complained of exertional dyspnea were enrolled. (Average age: 56.7짹10.5) Fifty six were non diabetic patients with MS(Group 1) while 56 patients were age-sex matched patients without MS(Group 2). Diastolic stress echo was performed using a symptom limited, multistage supine bicycle exercise test. Variable Doppler parameters were obtained at baseline, at each stage of exercise, and during recovery. Results: There was no significant difference in terms of age, gender and hemodynamic variables such as BP, heart rate and ejection fraction(EF) at rest and during peak exercise between two groups. Although there was no significant difference in LV dimension and baseline EF, group 1 demonstrated significantly higher relative wall thickness and LV mass index. E/E���, an index of LV filling pressure, was significantly higher in patients with MS at rest and during exercise. Annular systolic tissue velocity(S���) was not different at rest but the change of S��� from baseline to peak exercise, the longitudinal contractile reserve, was significantly lower in the MS group. (2.00 짹 1.65 vs 2.90 짹 1.66, P = 0.015) At peak exercise, S��� was significantly lower in the MS group. Multiple regression analysis showed the independent association of MS with longitudinal contractile reserve when controlled for confounding factors such as LV mass index, gender, blood pressure and age. (棺 = - 0.235, P = 0.035) Conclusion: Longitudinal contractile reserve was reduced in patients with MS compared to patients without MS although both group demonstrated similar longitudinal contractile function at rest. We demonstrated, for the first time, that metabolic syndrome is independently associated with LV systolic dysfunction during exercise in hypertensive patients.