Exposure to sulphur mustard (SM) gas may have extensive immediate effects on the respiratory system. However, long-term effects are far less known. This case report describes a Kurdish male child who was exposed to SM gas during a chemical attack in Iraq at 5 yrs of age. In the acute phase, the child developed severe respiratory symptoms with a chemical pneumonia. Extensive burning of the skin occurred. In the course of 10 yrs, lung function deteriorated progressively to a forced expiratory volume in one second of 30% of predicted value. Severe air-trapping occurred. The lung function abnormalities were not reversed by treatment with corticosteroids or bronchodilators. Infectious exacerbations of the child's lung disease occurred. High resolution computed tomography scan showed multiple bronchiectasis. The histological picture of an open lung biopsy was best described as a "chronic bronchiolitis".