BACKGROUND: Corticosteroid is most potent and effective anti-inflammatory medication currently available and inhaled form has been used in the long-term control of asthma. Fluticasone propionate(Flixotide/Flovent : FP) is highly potent and topically active inhaled corticosteroid and has at least twice the potency of beclomethasone dipropionate(BDP) in the control of asthma. The aim of this study was to compare the efficacy of FP and BDP in several aspects. METHOD: Fifty patients with asthma were treated in a randomized, parallel group study of 4 weeks duration. During 2-week run-in period beta2-agonist was administered. After run-in period, FP 500 micro gram/day was administered via Diskhaler or BDP 800 micro gram/day via reservoir dry-power device. During the run-in and treatment period, morning and evening peak expiratory flow rate(PEFR) were measured daily. Daytime and night-time asthma symptoms, daytime and night-time rescue bronchodilator use were checked daily. FEV1.0 and FVC were measured biweekly in both groups. RESULTS: Three patients treated with FP and seven patient treated with BDP were dropped out. Therefore forty patients completed the study. Morning and evening PEFR was increased and diurnal variation of PEFR decreased significantly in both groups. FEV1.0 increased significantly in FP treatment group but not in BDP group. There were also improvements in daytime and night-time asthma symptoms, daytime and night-time rescue bronchodilator use in both groups after treatment. there were no significant difference between groups in any of the efficacy parameters. Therapeutic effects were dimonstrated earlier in patient treated with FP than BDP. CONCLUSION: In this study, 500 micro gram/day fluticasone propionate was as effective as 800 micro gram/day beclomethasone dipropionate in the control of asthma. Therapeutic effects were demonstrated earlier in patient treated with FP than BDP without adverse effect.