The effects of additional target-flow inspiratory muscle training (TF-IMT) on the performance of the inspiratory muscles, on general exercise capacity, and on psychologic parameters during a pulmonary rehabilitation program (PR) were studied in 40 patients with COPD selected for ventilatory limitation during exercise. The mean age of the patients was 59 years, and the mean FEV1 was approximately 50 percent of predicted. All patients participated in a ten-week PR program. They were randomized to receive either additional TF-IMT (PR + IMT) or not (PR). The TF-IMT was performed by means of a target-flow resistive device; the generated mouth pressure and the duration of inspiration and of the respiratory cycle were imposed. After the training period, maximal inspiratory mouth pressure and EMG-fatigability of the diaphragm were significantly better in the PR + IMT group than in the PR group. Maximal work load and psychologic symptoms increased to the same extent in both groups. The 12-minute walking distance also increased in both groups, but it increased significantly more in the PR + IMT group than in the PR group. We believe that additional TF-IMT during PR in a selected group of patients with COPD who have ventilatory limitation has an extra beneficial effect on the performance of the inspiratory muscles and on exercise performance.