BACKGROUND/AIMS: Carotegrast methyl, an oral alpha4-integrin inhibitor, was recently approved for the treatment of active ulcerative colitis (UC). However, real-world data regarding its efficacy and safety remain scarce. This study aimed to assess the clinical effectiveness and safety profile of carotegrast methyl in patients with active UC. METHODS: Patients with active UC received carotegrast methyl at a dosage of 960 mg three times daily. Treatment was discontinued at 8 weeks for patients who achieved endoscopic remission. For those not achieving endoscopic remission, treatment was continued for up to 24 weeks. Clinical and endoscopic assessments were performed at 8 and 24 weeks to evaluate treatment progress. RESULTS: Among 50 UC patients, 45% achieved clinical remission, and 22% achieved endoscopic remission by week 8. Of those who discontinued treatment after reaching endoscopic remission, 55% experienced relapse during a median follow-up period of 30 weeks. For patients who continued treatment through 24 weeks, 52% achieved clinical remission, with a cumulative remission maintenance rate of 74.2%. Mild adverse events were reported in 6% of patients, including hyperamylasemia, hepatic dysfunction, and elevated biliary enzymes, all of which resolved after discontinuation of treatment. In 8 patients who relapsed and were re-administered carotegrast methyl, 62.5% achieved clinical remission, demonstrating the drug's effectiveness and safety in re-treatment. CONCLUSIONS: Carotegrast methyl effectively induces both clinical and endoscopic remission in patients with active UC and has a favorable safety profile. Re-administration is safe and effective for patients experiencing relapse.