['Rehabilitation is a central treatment modality for patients with chronic cardiopulmonary disease. Physical exertion for patients with pulmonary arterial hypertension (PAH) has typically been discouraged. Inpatient pulmonary rehabilitation has been shown to improve exercise capacity in patients with PAH. The present study aimed to evaluate outpatient pulmonary rehabilitation for patients with PAH.', 'Twenty-two patients with PAH or chronic pulmonary thromboembolic disease were allocated to ambulatory rehabilitation (n = 11) or to the control group (n = 11). All patients were stable on PAH-specific medication. The rehabilitation group underwent 24 1-hour sessions of exercise training/rehabilitation over 12 weeks. Primary end points were change in 6-minute walking distance (6MWD) and peak oxygen uptake (VO(2)) on cardiopulmonary exercise testing. All of the patients assigned to rehabilitation and 9 control subjects completed the study. In the rehabilitation group, 6MWD increased by 32 m, and in the control group 6MWD decreased by 26 meters (P = .003). Peak VO(2) increased in the rehabilitation group by 1.1 mL kg(-1) min(-1) and decreased by 0.5 mL kg(-1) min(-1) in the control group (P\xa0< .05). Peak work rate during cardiopulmonary exercise test also increased in the rehabilitation group, with borderline significance (P = .051). Echocardiography and blood N-terminal pro-brain natriuretic peptide levels were unchanged. No adverse events occurred due to the rehabilitation program.'] Does ambulatory rehabilitation improve exercise capacity in patients with pulmonary hypertension?