Invasive aspergillosis is frequently a fatal disease in the setting of immunosuppression, including organ transplant recipients. The fungus usually affects lung parenchyma and may disseminate from there. We have recently noted tracheobronchitis in six patients with heart-lung and lung transplants, three of whom had deep mucosal ulceration and histologic evidence of invasive aspergillosis. This apparently new form of invasive disease is initially limited to the anastomosis site and large airways. Ulceration, necrosis, cartilage invasion, and formation of a pseudomembrane are the pathologic features. In two patients subsequent disseminated aspergillosis occurred with a fatal outcome. In the two single-lung recipients, disease was limited to the transplanted side emphasizing the importance of abnormal local defense mechanisms in the airways of lung transplant recipients. Routine bronchoscopic examination of the airways is important in early detection of this complication. Oral therapy with the new, antifungal agent itraconazole was successful in five of the six patients, with fatal relapse in one. A classification of the various forms of saprophytic, allergic, and invasive forms of aspergillus tracheobronchitis, to include this new entity, is proposed.