Aspergillus is a genus of fungi commonly found in all environments. Remarkably, only a few species cause disease and equally remarkably, those same species cause multiple diseases. In the lung, exposure to the fungus, the immunological status of the individual and the condition of the lung determine the pattern of disease. In asthmatic patients and those with cystic fibrosis, allergic bronchopulmonary aspergillosis (ABPA) is a complication that reduces pulmonary function and, in asthmatics, is substantially improved by itraconazole therapy. Patients with pre-existing lung cavities develop aspergillomas (fungal masses inside the cavity). Aspergillomas carry a 40% 5 years survival, and it not clear whether antifungal therapy is helpful. Simil...