Sinobronchial syndrome (SBS) is characterized by chronic sinusitis with chronic infection of the bronchus. Chronic bronchitis, bronchiectasis and diffuse panbronchiolitis are also examples of complicating lower airway disease. In Japan, the surgical treatment of sinusitis is not considered to improve the lower airway diseases. Most published reports describe the Caldwell-Luc method. However ESS (Endoscopic Sinus Surgery) can heal sinusitis while maintaining the morphology and function of the paranasal sinus. In addition, its surgical results are satisfactory. This report describes the improvement of patients with SBS who underwent ESS. Twelve patients with sinobronchial syndrome who underwent ESS at our department between 1989 and 1993 were enrolled in the study. Subjective improvement in sinusitis and the lower airway diseases were evaluated using a questionnaire. Objective improvements in sinusitis were evaluated using endoscopic findings of the ethmoid sinuses, while objective improvements in the lower airway diseases were evaluated by measuring the vital capacity and FEV 1.0%. These examinations were performed one year after the operation; the results of long-term follow-up examinations performed more than 6 years after the operation were also studied. In all of the patients, subjective nasal symptoms and objective endoscopic findings were satisfactory, with improvement rates of 91.7% and 83.3%, respectively. Regarding the lower airway symptoms, all the patients subjectively rated the symptoms as having improved, and an improvement in the FEV 1.0% was improved in all of the cases. In the present study, the lower airway symptoms improved after ESS. ESS enables the paranasal sinuses to be treated while maintaining the morphology of the paranasal sinus. Consequently, surgical results are better. The improvement of chronic sinusitis reduces the direct inflow of postnasal drippings into the bronchus. Restoring the normal functions of the nasal sinus defends the lower airway by warning, and humidifying the inspiratory air and removing dusts; these functions are though to have a favorable effect on the lower airway.