ABPA may occur in patients with longstanding bronchial asthma. The most important diagnostic criteria include a history of asthma with peripheral blood eosinophilia, immediate skin reactivity, elevated serum IgE, precipitating antibodies against Aspergillus species, migrating infiltrates, and central bronchiectases. Here we report on the clinical characteristics in 15 patients in whom the diagnosis of ABPA could be established. Mean diagnostic latency between the occurrence of first symptoms and the diagnosis was 10 +/- 10 years. We therefore conclude that the diagnosis and therapy of ABPA is often delayed.