Allergic bronchopulmonary aspergillosis (ABPA) is a complex allergic disorder caused by immune reactions against Aspergillus fumigatus. ABPA most commonly complicates the course of patients with poorly controlled asthma. Patients commonly present with uncontrolled asthma, fleeting pulmonary opacities, and bronchiectasis. Pathogenetically, ABPA is characterized by the persistence of A. fumigatus in the airways and an exaggerated type-2 immune response. The interest in ABPA stems from the fact that bronchiectasis in ABPA can be prevented if the disorder is diagnosed timely and treated appropriately. Herein, we summarize the current concepts in the epidemiology, pathogenesis, diagnosis, and treatment of ABPA.