Allergic bronchopulmonary aspergillosis (ABPA) is a known complication in patients with bronchial asthma and cystic fibrosis. The estimated number of unknown cases is very high. There is a great latency between symptoms and diagnosis of this disease. Diagnostic criteria involve anamnesis, pulmonary infiltrates, sensitization against Aspergillus species, and predominant central bronchiectasis. IgE and IgG antibodies against Aspergillus fumigatus are important elements for diagnosis. Treatment with corticosteroids is recommended. In severe courses, additional antimycotic therapy should be considered.