Seven patients with severe, unexplained chronic bronchial suppuration and inflammatory bowel disease are reported. In three, rapidly progressive bronchiectasis developed within one year of procto-colectomy, in two it developed in association with an exacerbation of colitis and in the other two a milder, limited colitis post-dated the start of the lung disease. The high incidence of arthropathy and skin rashes suggests a systemic disease, and personal and family histories of auto-immune conditions were common. Antinuclear antibodies were detected in six and smooth muscle antibodies in five of the seven patients and there was no evidence of liver disease. Evidence of circulating immune complexes was found in two patients. In the four patients who received corticosteroid therapy there was an impressive improvement in cough, sputum volume and dyspnoea, especially when taking high doses. Because of the time relationships of the bowel and lung symptoms we suggest that these disorders may be related.