Two patients with allergic bronchopulmonary aspergillosis (ABPA) have been treated with a high dose (1600 micrograms daily) of inhaled corticosteroid for 18 months. A beneficial effect with regard to asthmatic symptoms was observed in both patients. During the first 14 months of the observation period no significant changes were observed in lung function parameters. Bronchial histamine challenge showed decreased hyperreactivity. IgE decreased in both patients, while specific IgE and IgG remained the same. After 14 months of treatment one of the patients developed severe, acute exacerbation of the ABPA and was treated with high-dose prednisolone and local steroid. The patient is now fully recovered and has continued on local steroid therapy. The other patient had no episodes of exacerbation and remains stable on this treatment.