Background: Chronic obstructive pulmonary disease (COPD) is a disease state characterized by progressive airflow limitation and is associated with an abnormal inflammatory response of the lungs to noxious particles or gases, primarily caused by cigarette smoking. Pulmonary hypertension primarily occurs in COPD patients with severe hypoxemia and fortunately it is typically mild. Hypoxemia increases pulmonary artery pressure (PAP) through hypoxic pulmonary vasoconstriction and vascular remodeling, but there is a correlation between lung function parameters and PAP, suggesting that factors other than airway obstruction and/or loss of alveolar surface may play a role in its etiology. Objective: The aim of the work was to Identify other factors other than resting hypoxemia contributing to pulmonary hypertension in COPD patients.  Patients and Methods: This study was a prospective study including 80 cases referred to Ain Shams University Hospitals presented with COPD defined using the standard criteria for chronic bronchitis. All patients underwent spirometry with pre and post bronchodilator treatment and trans-thoracic echocardiography. Results: The results showed that there was significant correlation between right ventricular systolic pressure (RVSP) values and each of the following; age, duration of smoking and degree of airway obstruction which were all contributing to pulmonary hypertension in COPD patients.  Among 80 patients, 18 had elevated RVSP value. The mean age of those 18 patients was 58.8 ± 7.78 years while in those with normal RVSP 54.15±10.56 years. Those 18 patients had mean FEV1 percentage of predicted 44.5 ± 12.1% while in those with normal RVSP value 48.72±1.62%. Among those 18 patients 16 had history of smoking for >20 years representing 88.9%. Multivariate analysis showed that among all the studied parameters in our study, degree of obstruction determined by measured FEV1 percentage of predicted is an independent predictor for pulmonary hypertension in stable COPD patients. Conclusion: It could be concluded that pulmonary hypertension occurs frequently in stable COPD outpatients without resting hypoxemia and that age, duration of smoking and low pre-bronchodilator FEV1 are all risk factors for pulmonary hypertension. And that degree of airway obstruction is an independent predictor for pulmonary hypertension in stable COPD patients.