The use of high dose inhaled beclomethasone dipropionate (BDP) as a means of assessing steroid responsiveness in chronic obstructive airways disease (COAD) was assessed in 22 patients in a study involving three consecutive 2-week periods of placebo, inhaled BDP (1500 micrograms daily), and oral prednisolone (30 mg daily). Five of the 22 patients were considered steroid responsive following the course of oral corticosteroids and in each case this responsiveness had been identified by inhaled BDP therapy. It is concluded that high dose inhaled BDP (1500 micrograms daily) may be used to assess corticosteroid responsiveness in COAD.