In 48 patients with chronic asthma who had been receiving treatment with beclomethasone dipropionate aerosol (BDA) at a daily dose of 400 microgram for several years, observations were made on the effect of increasing the dose to 800 microgram daily for 6 months. 2. There was subjective improvement in 37 of the 48 patients, but the only objective evidence of improvement was a slight reduction in airways resistance. 3. The higher dose of BDA did not produce impairment of pituitary-adrenal function or an increase in the incidence of oropharyngeal candidiasis.