The effects on pulmonary function tests and exercise tolerance of resistive breathing training (RBT) were assessed in 16 subjects with stable chronic obstructive pulmonary disease (COPD) who had received no benefit from previous programs of breathing retraining (BR) and medical therapy (MT). 16 male patients with mild degree stable COPD underwent detailed evaluation of pulmonary function tests, blood gas analysis and exercise tolerance test before and after a monthly program of RBT. The patients had received no physiological effects from previous monthly programs of BR and MT. No change in pulmonary function tests, blood gas analysis and exercise tolerance test was observed after RBT. Only maximal static expiratory pressure increased significantly after RBT. We conclude that RBT does not improve pulmonary function tests in subjects who received no physiological benefit from BR.