The objective of this investigation was to evaluate gas exchange and cardiopulmonary functional behavior in patients with pulmonary hypertension (PH) before, during and after the change to a prone position. Thirty patients with PH and alterations in gas exchange were included in the study. Gas exchange measurements were performed in four stages: at the baseline supine position and after 30, 120 and 240 minutes in prone position. Also, the patients were evaluated by the six minutes walking test (6MWT) after 30 days in prone position during night's sleep. After four hours in prone position, all patients showed an increase of PaO2 and arterial saturation of oxygen (SaO2), with a decrease of intrapulmonary shunts, improving the gas exchange and therefore the physiological demand imposed by exercise in patients with PH.