Kazuya Horiuchi, Keita Kasahara, Yusuke Kuroda, Haruna Morohoshi, Yosuke Hagiwara, Gen Ishii Respiratory Disease Center, Showa University Northern Yokohama Hospital, Yokohama-shi, Kanagawa-ken, Japan Purpose: A combination therapy with inhaled corticosteroid (ICS) and a long-acting β agonist (LABA) is the standard treatment for asthmatic patients, and step-down treatment is recommended once control has been achieved. However, little data exist that evaluate the long-term outcomes after step-down treatment. Objective: To compare the long-term outcomes of step-down therapy with ICS/LABA or ICS alone for asthmatic patients who have achieved well-controlled asthma by the ICS (250 µg fluticasone)/LABA (50 µg salmeterol) combination (SFC, two puffs per day). Patients and methods: We randomized 40 well-controlled patients with asthma receiving SFC (250 µg) to two groups; one group of patients received step-down therapy with low-dose SFC (100 µg, two puffs daily) and another group of patients received step-down therapy with high-dose fluticasone propionate (FP) alone (500 µg, daily). The two groups were monitored over 12 months for changes in asthma control test scores, respiratory function (percent forced expiratory volume in 1 second, maximal expiratory flow rate at 50% of the vital capacity [%FEF50], and maximal expiratory flow rate at 25% of the vital capacity [%FEF25]), and the concentration of fractional exhaled nitric oxide. Results: There was no significant difference in the dropout rate between the SFC and FP groups. Low-dose SFC maintained the stability of all parameters over 12 months, whereas the FP group exhibited a rapid 5% decrease in forced expiratory volume in 1 second within 2 months after discontinuation of salmeterol; furthermore, after 10 months, there was a gradual decrease in %FEF50 and %FEF25. Conclusion: This study suggests that a balanced step-down protocol, including both ICS and LABA, is essential in providing long-term stability to patients with mild-to-moderate well-controlled asthma. Keywords: long-term outcome, asthma, fluticasone propionate, salmeterol, step down