Background: Pulmonary hypertension may develop during exercise and it has an adverse effect on the functional status, exercise tolerance and prognosis. However, the independent role of cardiac functional abnormalities in the genesis of pulmonary hypertension during exercise in subjects with normal systolic function is unclear. The purpose of this study was to analyze the determinants of exercise-induced pulmonary hypertension in patients with normal systolic function. Methods: Three hundred sixty-eight subjects (322 male, mean age 55짹13) who were referred for exercise echocardiography underwent a symptom-limited graded supine bicycle exercise and two-dimensional and Doppler echocardiographic study at the same time. Tricuspid regurgitation (TR) velocity was measured at rest and during exercise. Patients were classified according to the presence or absence of exercise-induced pulmonary hypertension, defined as exercise (50 W) TR velocity>3 m/sec. Results: One hundred eighty patients (49%) demonstrated an increase in TR velocity during exercise > 3 m/sec. Patients with exercise-induced pulmonary hypertension was older, more common in female, and had shorter exercise duration. However, ejection fraction was significantly higher in patients with exercise-induced pulmonary hypertension. Numerous echocardiographic variables were significantly different between two groups. In multivariate analysis, resting TR velocity (p<0.0001) and E/E���(p=0.027) were the strongest predictors of elevated TR velocity during exercise as well as age and gender. Conclusion: Exercise-induced pulmonary hypertension is common even in subjects with normal ejection fraction. It is strongly associated with left ventricular filling pressure as well as resting TR velocity, age and gender.