To evaluate the clinical efficacy of high dose inhaled steroids, we examined the effects of standard doses (400 micrograms/day) and high doses (800 micrograms/day) of inhaled beclomethasone dipropionate (BDP, Becotide Inhaler), and the dose for regular use (800 micrograms/day) of salbutamol (Salb. Asmidon Air) on pulmonary function, bronchial hyperresponsiveness and asthma attack score. The subjects were 17 out-patients with mild or moderate bronchial asthma who were not receiving any anti-allergics or steroids. The patients were randomly allocated into three groups i.e., Group I: BDP 400 micrograms/day, Group II: BDP 800 micrograms/day and Group III: Salb. 800 micrograms/day. The administration period was 8 weeks. Pulmonary function test were performed and bronchial hyperresponsiveness was examined before and after the 8 weeks of treatment and attack scores were recorded during this period. It was found that inhalations of 400 micrograms/day and 800 micrograms/day BDP improved FEV1.0% value, peak flow, F-V curve, Dmin. and SGrs/Grs cont. Particularly, inhalation of 800 micrograms/day of BDP significantly improved these values and reduced attack scores in the early stages of the 8 week treatment. In contrast, there was a trend for inhalation of Salbutamol to enhance bronchial hyperresponsiveness and not to improve pulmonary function and asthma attack score. In conclusion, 800 micrograms/day of inhaled BDP is considered to be useful in the treatment of mild or moderate bronchial asthma.