Sinobronchitis is a syndrome, which indicates a subacute or chronic inflammatory process involving the paranasal sinuses accompanied with an infection of the trachiobronchial mucosa and with hilar lymphnodes swelling.<BR>In this presentation, first the frequency of sinobronchitis was treated from the rhinologic standpoint. Second, the characteristic clinical findings were described. Third, the results of analysis of the sweat electrolytes in the patients with chronic sinusitis and sinobronchitis, and comparative observation between the histopathologic changes of the sinusal mucosa of the affected paranasal sinuses and those of the bronchial mucosa taken from the resected lung specimens with chronic bronchial inflammation were reported.; Finally, the long term prognosis of the patients with this syndrome were added.<BR>The results of the chest x-ray examination and the thorough investigations of the anamunesis and the complaint showed chronic bronchitis and bronchiectasis in 23 or 5% of 461 patients with chronic sinusitis, in 33 or 16% of 205 (primary, middle and high school, and university) students with chonic sinusitis, and in 2 or 10% of 20 miners with chonic sinusitis and polyposis.<BR>Besides headache, nasal obstruction, anterior and posterior nasal discharge, couching and expectoration were added as the synptomes of chronic bronchial disorders in almost all of the 38 cases, which suffered from sinobronchitis for about ten months. Nasal and sinusal changes were similar to those of the banal paranasal sinusitis. Chest x-ray findings of the patients with this syndrome were characterized occasionally by increased hilar marking, cloudiness in the lower lung field and emphysematous change (chronic bronchitis), and sometimes, by triangle shadow in the phrenicocardial angle, mediastenal shifting and honey comb shadow (bronchiectasis). The obstructive ventilatory insufficiency was occasionally found in the patients, even in youths, suffering from sinobronchitis.<BR>One hundred thirty patients suffering from chronic sinusitis and sinobronchitis were sudjected to the analysis of sweat electrolytes. The sweat for analysis was obtained by pilocarpine iontophoresis in all cases tested.<BR>If the level of more than 60meq/1 of chloride and the level of more than 70meq/1 of sodium could be considered as a high abnormal level, the following could be said.<BR>1) In eleven out of 130 cases tested the analysis of the sweat revealed the high abnormal level of both sweat chloride and sodium concentration.<BR>2) There was no relationship between the high abnormal level of both sweat chlocide and sodium and the opacity of paranasal sinuses on x-ray films or nasal polyposis.<BR>3) There was some relationships between the high abnormal level of both sweat chloride and sodium and the extent of the density in the lung field on x-ray films.<BR>4) Cases with sinobronchitis presented frequently elevated sweat electrolytes concentration.<BR>5) It was impossible to detect the case with fully manifested cystic fibrosis of the pancreas through the sweat test in Japanese with paranasal sinusitis and with sinobronchitis.<BR>Sinusal mucosa removed surgically from fourteen patients with sinobronchitis were classified histopathologically as follows: edematous 5, fibrotic 3, fibroglandular 3 and inflammatory 3. On the other hand, bronchial mucosa of the lung specimens with chronic bronchitis or bronchiectasis could be classified into four types. 1) The affected bronchial wall and the surrounding parenchyma of the lung have various inflammatory changes. 2) Chronic inflammatory processes develop predominantly on the bronchial wall alone. 3) The structural weakness of bronchial wall and emphysema are predominant, dispite little or no inflammatory change. 4) combined typy of 1) -3).