To clarify the prognosis of asthmatics treated with low-dose of inhaled beclomethasone dipropionate (BDP), we retrospectively assessed 43 patients treated with initial dose of 200 or 400 micrograms/day for 5 years, and obtained the following results. 1) 15 patients achieved step-down therapy (group A), 17 patients maintained initial dose of BDP (group B), and 11 patients required step-up therapy of BDP or daily use of oral prednisolone (group C). 2) There was no significant difference in age, sex, duration of disease, severity of disease, peripheral eosinophil counts, %FEV1 and histamine PC20 before BDP treatment among three groups. The percentage of atopic asthmatics was significantly higher in group C than in group A. 3) There was no significant difference in symptom and histamine PC20 between after 1 year state and after 5 years state in three groups. 4) After 1 year from the start of BDP treatment, only 18% patients got symptom free and neither patients exceeded 20,000 micrograms/ml of histamine PC20 in group C. Long-term treatment of low-dose BDP inhalation was effective on mild/moderate asthmatics. Patients requiring step-up therapy had not got sufficient improvement in bronchial hyperresponsiveness after one-year treatment.