Following lung transplantation for end-stage cystic fibrosis, two male patients presented with shortness of breath, peripheral blood eosinophilia and segmental lung collapse. At bronchoscopy, each had bronchial mucous plugging containing Aspergillus fumigatus. This finding was associated with a systemic eosinophilia and skin test positivity to Aspergillus. Augmented steroid therapy resulted in the successful resolution of the symptoms. We believe that these are the first reported cases of allergic bronchopulmonary aspergillosis in lung allograft recipients. ©ERS Journals Ltd 1996.