Exercise pulmonary hypertension is common in patients with chronic thromboembolic pulmonary hypertension who experience shortness of breath during exercise and reduced exercise capacity despite normalised pulmonary artery pressure at rest; however, the relationship between exercise pulmonary hypertension and exercise capacity remains unclear. Here we aimed to determine whether exercise pulmonary hypertension is related to exercise capacity and ventilatory efficiency in chronic thromboembolic pulmonary hypertension patients with normalised resting haemodynamic after pulmonary balloon angioplasty (BPA).Two hundred and forty-nine patients with chronic thromboembolic pulmonary hypertension treated with BPA (age, 63±14 years; men/women, 62/187) with normal mean pulmonary artery pressure (<25 mmHg) and wedge pressure (≤15 mmHg) at rest underwent cardiopulmonary exercise testing with a right heart catheter. The mean pulmonary artery pressure-cardiac output (mPAP-CO) during exercise was plotted in multiple points. Exercise pulmonary hypertension was defined by a mPAP-CO slope of greater than 3.At rest, the pulmonary vascular resistance was significantly higher in the exercise pulmonary hypertension group (n=116) than in the non-exercise pulmonary hypertension group (n=133). Lower peak oxygen consumption (13.5±3.8 versus 16.6±4.7 mL·min-1·kg-1, p<0.001) was observed in the former group. The mPAP-CO slope was negatively correlated with the peak oxygen consumption (r=-0.45, p<0.001) and positively correlated with the minute ventilation versus carbon dioxide output slope (r=0.39, p<0.001).Impaired exercise capacity and ventilatory efficiency were observed in patients with chronic thromboembolic pulmonary hypertension who had normalised pulmonary artery pressure at rest but exercise pulmonary hypertension.