Allergic bronchopulmonary aspergillosis is a complex clinical picture that mainly occurs in patients with cystic fibrosis and bronchial asthma. It is characterized immunologically by a specific IgE synthesis against A. fumigatus antigens, and increased IgG antibodies can often also be detected. Clinically, the disease leads to a deterioration in the general condition and reduced resilience of the patients with deterioration in the lung function parameters and in the course of the disease typical changes in the lung structure that can be demonstrated radiologically. The combination of these findings results in special diagnostic criteria. The diagnosis of cystic fibrosis is complicated by the fact that the diagnostic criteria overlap with symptoms of the underlying disease. Early diagnosis and therapy influence the prognosis and the development of chronic lung structure changes. In the case of cystic fibrosis, annual laboratory screening for ABPA is established; in the case of bronchial asthma, screening should be carried out early if the condition deteriorates clinically. Systemic glucocorticosteroids are primarily used therapeutically; the benefit of an additional antimycotic therapy has only been proven in adult asthmatics, but not in CF patients. Biologics could play an increasing role in treatment in the future.