The spectrum of respiratory diseases associated with ulcerative colitis. The respiratory diseases associated with ulcerative colitis have recently been recognized, and principally affect the bronchi. Both chronic bronchitis and bronchiectasis may develop after many years, some of the patients having already undergone colectomy. Chronic bronchitis is characterized by cough and chronic mucopurulent sputum, and these symptoms may be exacerbated during acute flare-ups of ulcerative colitis. The bronchial lesions are inflammatory and can be reversed by corticosteroid therapy. Bronchiectasis produces similar symptoms, but has distinctive radiological features. Corticosteroids may sometimes reduce the symptoms, but they have no effect on the bronchial lesions. Salicylazosulfapyridine might be responsible for hypersensitivity lung diseases with eosinophilia, but the drug does not seem to be involved in the genesis of these bronchial manifestations. There have been occasional reports of other respiratory diseases associated with ulcerative colitis, including obliterative bronchiolitis, isolated and asymptomatic airflow obstruction, inflammatory tracheal stenosis, pulmonary vasculitis, pleurisy and pleuropericarditis, chronic pneumonia and interstitial fibrosis which may be diffuse or localized to the apices.