 DHEA prevents and reverses chronic hypoxic pulmonary hypertension in a chronic hypoxic-pulmonary hypertension model in the rat. However, no study has been performed in human. The purpose of this study is to determine if DHEA is effective in the treatment of respiratory pulmonary hypertension in adults with Chronic Obstructive Pulmonary Disease COPD on exercise capacity and haemodynamic variables. Patients will receive after randomization either 200 mg oral DHEA or placebo over a one-year period. Evaluation concerns clinical parameters, echocardiography and right catheterization after and before treatment. Primary end-point is the six-minute walk test. This is a prospective double blind, randomized, placebo controlled study which will be realized in four university hospitals in France : Bordeaux, Strasbourg, Toulouse and Limoges. 