OBJECTIVE The benefits of pulmonary rehabilitation for patients with COPD depend on the intensity of training. Traditional pulmonary rehabilitation programmes (PRPs) do not consistently achieve high-intensity training and have variable training effects. This study examined the effects of high-intensity exercise training on cardiac and pulmonary function in COPD patients. METHODS Patients with COPD participated in a 6-week, cardiopulmonary exercise test-based PRP. Spirometry, 6-min walking distance and cardiopulmonary exercise test were used to evaluate cardiopulmonary function, respiratory muscle strength and endurance at rest, during exercise and before and after the programme. Patients were encouraged to complete high-intensity exercise with a targeted training intensity of at least 75% maximum oxygen uptake (VO(2)). RESULTS Thirty-four COPD patients were enrolled into the study; 16 completed the high-intensity training, 18 did not. At the end of the 12-session PRP, submaximal exercise capacity (6-min walking distance, 461.8 +/- 77.2-502.7 +/- 66.9 m, P < 0.001) improved in both the patients who completed high-intensity training and those who did not. Only the patients who completed high-intensity training had significant improvements in FVC (2.47 +/- 0.70-2.70 +/- 0.62 L, P = 0.024) at rest, maximal exercise capacity (peak VO(2), 1001.6 +/- 286.4-1116.1 +/- 320.4 mL/min, P = 0.020) and work efficiency (7.3 +/- 1.4-8.4 +/- 1.8 mL/min/watt, P = 0.026). There was no statistically significant difference between the two groups in the change in the physiological parameters before and after exercise. CONCLUSIONS Exercise training in a PRP improved submaximal exercise capacity. Only patients who completed high-intensity exercise training showed improvements in maximal exercise capacity, FVC and work efficiency.