Ventilatory function of the lungs was studied in 128 patients with expiratory stenosis of the trachea. In 39.1 percent of the patients, the disease ran its course alone, in 17.9 percent of the patients it was combined with bronchial asthma, and in 43 percent, with chronic bronchitis. It is concluded that the patients demonstrated no alterations in ventilation, characteristic of expiratory stenosis of the trachea. The time-course of changes in ventilation appeared to be determined by morphofunctional alterations in the bronchi as a sequela of chronic bronchitis and bronchial asthma.