Introduction: Budesonide MMX ® is approved for induction of remission in mild-to-moderate active ulcerative colitis (UC) in adults in whom 5-ASA is not sufficient. There is a lack of data on its effectiveness and safety in clinical practice., Material and Methods: The CORE Practice study was a multi-centre prospective, observational study of mild-to-moderate UC-patients treated with Budesonide MMX ® 9 mg for up to 8 weeks (induction). Enrolled patients had previously been prescribed Budesonide MMX ® 9 mg in accordance with the SmPC within a 5-day time window. The primary endpoint was the percentage of patients achieving a decrease ≥ 3 points in the UCDAI clinical sub-score at the end of the induction treatment. Other endpoints were clinical remission (decrease ≤ 1 in UCDAI clinical sub-score), resolution of symptoms, change in Short Inflammatory Bowel Disease Questionnaire (SIBD-Q) score, treatment satisfaction, and tolerability. This report presents results from the Polish study sites., Results: The data from a Polish subgroup of 181 patients with mild-to-moderate UC were analysed. Clinical improvement ≥ 3 points in the UCDAI at the end of treatment induction was achieved in 63.8% patients. Clinical remission was observed in 55.9% of patients at the end of the induction treatment. Full resolution of symptoms (rectal bleeding = 0 and stool frequency = 0) at the end of the Budesonide MMX ® treatment was achieved in 52.5% of patients. Significant improvement in quality of life was seen in mean SIBD-Q total score from 40 points at baseline to 56 points at last assessment ( p < 0.001). A treatment satisfaction score of more than 8 out of 10 was observed in 72.9% of patients. One patient discontinued Budesonide MMX ® due to an adverse event that was related to the study drug, which counted for less than 1% of patients., Conclusions: The data from the Polish subgroup of the real-life study CORE Practice confirms the clinical efficacy of Budesonide MMX ® 9 mg in the majority of patients with active mild-to-moderate UC. Budesonide MMX ® was safe and well tolerated. The therapy was satisfactory for patients and showed a beneficial effect on the patients' quality of life., Competing Interests: M.J. is an employee of Ferring Pharmaceuticals, G.R. has received grants/research support or speakers fees from Abbvie, AlfaSigma, Astellas, Ferring, Janssen, Pfizer, Pharmabest, Recordatti, Sanprobi, Sandoz, Vitama, and Takeda declare paid and unpaid consultancies and honoraria for lectures from Ferring company. S.D. has served as a speaker, consultant, and advisory board member for Schering-Plough, Abbott (AbbVie) Laboratories, Merck and Co, UCB Pharma, Ferring, Cellerix, Millenium Takeda, Nycomed, Pharmacosmos, Actelion, α Wasserman, Genentech, Grunenthal, Pfizer, Astra Zeneca, Novo Nordisk, Cosmo Pharmaceuticals, Vifor, and Johnson and Johnson. K.P. is employee of Ferring Pharmaceuticals., (Copyright © 2023 Termedia.)