Summary: Allergic bronchopulmonary aspergillosis (ABPA) is a rare pulmonary disease that results from an exuberant inflammatory response to Aspergillus fumigatus colonizing the airways of patients with asthma, cystic fibrosis, bronchiectasis, and COPD. The key elements in the pathogenesis of ABPA are genetic predisposition, supporting colonization of the respiratory tract by Aspergillus fumigatus, and a skewed type 2 immune response. The diagnosis is based on the combination of suggestive clinical manifestations, consistent radiological presentation, sensitization to Aspergillus, and presence of immune activity markers. The recommended first-line treatment for ABPA is glucocorticosteroids or itraconazole administered orally for four months. However, after treatment cessation, nearly 50% of patients can experience ABPA exacerbations. Then, the management options include using prednisolone, itraconazole, or their combinations. Biological agents may be used as an option for managing treatment-dependent ABPA. Early diagnosis and proper treatment of ABPA are key to delaying or preventing the development of bronchiectasis. The recently revised ISHAM-ABPA working group clinical practice guidelines for diagnosing, classifying, and treating ABPA recommend evaluating Aspergillus sensitization in all newly diagnosed asthmatic adults in tertiary care settings using Aspergillus fumigatus-specific IgE. This article provides an in-depth overview of issues related to diagnosing, updating the clinical and radiological classifications of, and treating patients with ABPA.