Severe obstructive airways disease developed in 4 young nonsmoking adults after marrow transplantation. They were free of respiratory disease until symptoms developed 277 to 600 days after transplant. Pulmonary function testing showed that the mean forced expiratory volume in one second was 35% of predicted (range, 23 to 49%). All patients had active or inactive extensive chronic graft-versus-host disease that included oral mucositis, esophagitis, sinusitis, and oral and ocular sicca. Three patients had subnormal serum IgA levels. Bronchitis was apparent during fiberoptic bronchoscopy in 3 patients. An open-lung biopsy specimen from 1 patient showed obliterative bronchiolitis. Treatment has included bronchodilators and corticosteroids without objective benefit. The disorder stabilized in all 4 patients, but a severe reduction in air flow persisted. Awareness of this complication may lead to earlier diagnosis and more effective treatment.