For the re-expansion of refractory atelectasis, it is necessary to remove sputum in the airway and to deliver the intrabronchial positive pressure to the atelectatic lobe in order to overcome the critical opening pressure of the alveoli. Selective intrabronchial air insufflation is effective for this purpose, because with this procedure, endobronchial pressure in the atelectatic region can be selectively increased without elevation of the pleural surface pressure in the surrounding region of the lung. The inflator devised consisted of a flexible bronchofiberscope with a small balloon cuff at the distal end; through the fiberscope air was insufflated into the atelectatic lung. Using our procedure, we successfully performed intrabronchial insufflation in 14 of 15 patients with atelectasis, who had failed to respond to conventional therapy. In six patients, atelectasis recurred, and the same treatment was successfully performed again.