Abstract Background Allergic bronchopulmonary aspergillosis (ABPA) is a bronchopulmonary disease caused by a complex hypersensitivity to Aspergillus and is usually associated with underlying respiratory diseases such as asthma or cystic fibrosis. Mucus plugging can lead to segmental or lobar atelectasis, but complete lung atelectasis has been exceptionally reported in the literature, making it difficult to diagnose. The diagnosis of ABPA may however be suggested in patients without known predisposing respiratory disorder, even in the absence of other relevant radiographic findings. Case presentation We report five cases of total unilateral lung collapse secondary to ABPA in 70–81-year-old women. Two of them had a past history of ABPA, while total unilateral lung collapse was the first sign of the disease in the other three patients, contributing to the initial misdiagnosis. Flexible bronchoscopy was initially performed to remove mucus plugs from the obstructed airways but was inefficient in four cases. Corticosteroid and/or antifungal treatment was needed. Conclusion ABPA can cause total unilateral lung collapse even in patients without known underlying chronic respiratory disease, making the diagnosis difficult. Flexible bronchoscopy should be considered when lung collapse is associated with respiratory distress but corticosteroids are the mainstay treatment for ABPA.