BACKGROUND/AIMS: Etrasimod is an oral, once-daily, selective sphingosine 1-phosphate1,4,5 receptor modulator for the treatment of moderately to severely active ulcerative colitis (UC). However, its efficacy, safety, and the appropriate dosage have not been extensively investigated in the Japanese population. METHODS: This phase 2, multicenter, randomized, double-blind, placebo-controlled dose-ranging, 12-week trial was carried out among Japanese patients with moderately to severely active UC. Patients were randomized 1:1:1 to receive etrasimod 1 mg once daily (QD), etrasimod 2 mg QD, or placebo. The primary efficacy endpoint was the proportion of patients achieving clinical remission at week 12. Secondary efficacy endpoints and treatmentemergent adverse events (TEAEs) were also investigated. Efficacy endpoints were presented as proportions of patients achieving each outcome. RESULTS: Overall, 17, 19, and 18 patients received etrasimod 1 mg QD, etrasimod 2 mg QD, and placebo, respectively. One patient receiving etrasimod 1 mg (6.7%), 5 patients receiving etrasimod 2 mg (26.3%), and no patients receiving placebo (0%) achieved clinical remission. More patients receiving etrasimod versus placebo achieved secondary endpoints, except endoscopic normalization, at week 12. TEAEs were experienced by 9 patients receiving etrasimod 1 mg (52.9%), 13 patients receiving etrasimod 2 mg (68.4%), and 10 patients receiving placebo (55.6%). None of the TEAEs were serious and none experienced by patients receiving etrasimod led to treatment discontinuation. CONCLUSIONS: Overall, etrasimod 2 mg QD for up to 12 weeks appeared efficacious and safe in these Japanese patients with moderately to severely active UC. All TEAEs were mild to moderate in severity. (ClinicalTrials.gov: NCT05061446).