We examined the influence of septal deviations on pulmonary function in 247 study patients, and compared results with a control group of 387 patients without septal deformities. Tracheobronchial resistance, functional residual capacity and nasal resistance were measured by body plethysmography. Those patients with septal deformities had a 2.4 mm mean increase of tracheobronchial resistance, which was highly significant using the T-test between the two groups (P 1/2, 0.003%). We presume a probable reflex influence for this. However, the functional residual capacity in these patients was not significantly increased. Comparative measurements of pulmonary function before and after septal surgery showed decrease of tracheobronchial resistance in 66.7% of the patients. As a result of these findings, we believe that a close interdependence between nasal and pulmonary function seem probable.