We studied the clinical effect of a combination aerosol containing salbutamol and beclomethasone dipropionate in comparison to doubling the standard dose of salbutamol from an inhaler. Fifty-seven patients completed the double-blind, crossover study. They were treated with either an aerosol of 100 micrograms beclomethasone dipropionate and 200 micrograms salbutamol or 400 micrograms salbutamol alone. Both regimens were administered four times a day for 4 weeks. The patients showed significant improvement in FEV1, PEFR, and symptom scores after treatment with beclomethasone dipropionate and salbutamol compared with pre-trial values and with treatment with double the dose of salbutamol. The patients demonstrated a clear preference for treatment with the combination of beclomethasone dipropionate and salbutamol. Regular treatment with beclomethasone dipropionate in addition to salbutamol as a combination inhaler provides much better control of asthma than merely increasing the dose of salbutamol in those patients poorly controlled on standard doses of inhaled bronchodilators.