In this study, 4 patients who had failed weaning attempts using traditional methods underwent inspiratory muscle resistive training (IRT). Three patients showed improvements in inspiratory muscle strength (mean peak negative inspiratory pressure improved from 38 to 54 cm H2O) and in respiratory muscle endurance (mean PCO2 at the end of the same or a longer period of spontaneous breathing improved from 70 to 52 mmHg). These 3 patients were successfully weaned from mechanical ventilation after 10 to 24 days of IRT. A fourth patient showed no improvement and could not be weaned. This pilot study demonstrated that IRT can be useful in preparing patients with chronic respiratory failure for weaning from mechanical ventilation.