An open long-term trial of inhaled beclomethasone dipropionate was carried out in 32 asthmatic patients chronically dependent on systemic corticosteroids. Our objectives were to study the efficacy and safety of beclomethasone and to determine the proportion of patients in whom systemic steroids could be replaced by the new drug. All subjects had a clear history and physical findings of asthma as well as significant improvement in respiratory function after inhalation of salbutamol. Patients were followed for 4 to 8 years. Compared with a baseline period, patients receiving beclomethasone had reduced symptoms and needed less bronchodilator therapy, but their pulmonary function was unchanged. Bronchial biopsy specimens from seven patients who had been taking beclomethasone for as long as 8 years did not differ histologically from specimens from five asthmatic patients who had never taken the drug. Nine patients were able to stop taking systemic corticosteroids within 9 months, eight required them occasionally, and in eight the requirement was substantially reduced; the requirement did not change appreciably in the remaining seven. Inhaled beclomethasone is a safe and effective drug for chronic administration to asthmatic patients, and in 78% of our subjects the need for systemic steroids was substantially reduced or eliminated.