Allergic bronchopulmonary aspergillosis is an uncommon but serious respiratory condition characterized by chronic airway inflammation and airway damage resulting from persistent colonization by and sensitization to the fungus Aspergillus fumigatus. The immunopathogenesis of allergic bronchopulmonary aspergillosis involves several pathways. Aspergillus allergens stimulate an interleukin 5-mediated Th2 pathway responsible for the eosinophilic infiltrate, whereas aspergillus proteases promote epithelial activation and a potent chemokine response that induces neutrophilic airway inflammation. The resulting airway inflammation is intense, involves tissue damage and remodeling, and is linked with the severity of bronchiectasis. Treatment involves corticosteroids and antifungal therapy with oral azoles. Additional management seeks to monitor and control the other disease components of severe asthma, bronchiectasis, and disease exacerbations.