A clinical comparison of conventional aerosol administration of beclomethasone dipropionate and insufflation as a powder using the "Rotahaler" device in four doses of 100 microgram each was made in thirty-seven cases. Each treatment was given for 4 weeks, the order being randomized. Symptom records, twice daily peak flow readings and records of bronchodilator and steroid dosage showed the powder to be as effective as the aerosol. In the physician's opinion the powder was preferable to the aerosol in some cases.