Background: Pulmonary heart disease is the third commonest cardiac condition, next to hypertensive heart disease and artherosclerotic heart disease. Chronic obstructive pulmonary disease (COPD) is a common cause of pulmonary parenchymal disease that results in right ventricular dysfunction. In recent years, there have been a few studies suggesting that patient with COPD with pulmonary hypertension have right ventricular diastolic dysfunction. The aim of this study is to evaluate right ventricular diastolic function in a group of patient with COPD with and without cor pulmonale. Methods: 80 patients with COPD were stuided. Patients were divided into 3 subgroups accoding to cor pulmonale and pulmonary hypertension. 20 patients with cor pulmonale is group 1. 30 patients without cor pulmonale and pulmonary hypertension is group 2. 30 patients with pulmonary hypertension is group 3. COPD defined by American Thorasic Society classification. Cor pulmonale defined by ECG. The following variables were measured; peak velocity of early diastolic filling (E), late filling with atrial contraction (A), E/A ratio, and deceleration time of the E. Results: Patients with COPD with cor pulmonale and COPD with pulmonary hypertension had higher tricuspid peak A velocity, lower tricuspid E velocity, lower E/A ratio, than patients with COPD without cor pulmonale and pulmonary hypertension.(table) Conclusions: We can conclude that in patients with COPD, the development of pulmonary hypertension and cor pulmonale leads to right ventricular diastolic dysfunction whereas the patient without cor pulmonale and pulmonary hypertension are spared from right ventricular dysfunction.