Aspergillus fumigatusinfection is responsible for the majority of human and animal aspergillosis disease, even though air sampling studies show that its conidia usually comprise only a small percentage of total airborne fungal challenge. It is both a primary and opportunistic pathogen, and it is particularly troublesome for patients with cystic fibrosis. It causes multiple lung diseases, includingchronic pulmonary aspergillosis, allergic bronchopulmonary aspergillosis, and invasive pulmonary aspergillosis. Aspergillomas also occur in patients with cavitary lung diseases. Together, these diseases cause significant morbidity and mortality, and available treatments are suboptimal. Most patients with chronic pulmonary aspergillosis require antifungal therapy for many months or years, many experience significant drug side effects, and some experience drug resistance. Patients with either allergic bronchopulmonary aspergillosis (ABPA) or severe asthma with fungal sensitization can improve with itraconazole treatment, but relapses are common, and itraconazole affects corticosteroid metabolism and has the potential to worsen steroid side effects. ABPA requires long-term treatment because Aspergillus airway colonization is difficult to eradicate and quickly recurs when treatment is stopped. Immunocompromised patients are especially vulnerable to invasive aspergillosis where the mortality rate is often 50%, even with antifungal treatment. Clearly, therefore, new treatment approaches are needed for lung diseases caused by A. fumigatus, and we are proposing an approach based on prevention of binding to airway mucins. Adherence of A. fumigatus conidia to host tissues has been the subject of extensive research, but little attention has been directed to Aspergillus/mucin interactions, a surprising deficiency given the role mucins play in airway biology.