Budesonide MMX is a novel oral formulation of budesonide that uses Multi-Matrix System (MMX) technology to extend release to the colon. This study compared the efficacy of budesonide MMX with placebo in patients with active, mild-to-moderate ulcerative colitis (UC). Design Patients were randomised 1:1:1:1 to receive budesonide MMX 9 mg or 6 mg, or Entocort EC 9 mg (budesonide controlled ileal-release capsules; reference arm) or placebo once daily for 8 weeks. The primary endpoint was combined clinical and endoscopic remission, defined as UC Disease Activity Index score =1 with a score of 0 for rectal bleeding and stool frequency, no mucosal friability on colonoscopy, and a =1-point reduction in endoscopic index score from baseline. Results 410 patients were evaluated for efficacy. Combined clinical and endoscopic remission rates with budesonide MMX 9 mg or 6 mg, Entocort EC and placebo were 17.4 , 8.3 , 12.6 and 4.5 , respectively. The difference between budesonide MMX 9 mg and placebo was significant (OR 4.49; 95 CI 1.47 to 13.72; p=0.0047). Budesonide MMX 9 mg was associated with numerically higher rates of clinical (42.2 vs 33.7 ) and endoscopic improvement (42.2 vs 31.5 ) versus placebo. The rate of histological healing (16.5 vs 6.7 ; p=0.0361) and proportion of patients with symptom resolution (23.9 vs 11.2 ; p=0.0220) were significantly higher for budesonide MMX 9 mg than placebo. Adverse event profiles were similar across groups. Conclusion Budesonide MMX 9 mg was safe and more effective than placebo at inducing combined clinical and endoscopic remission in patients with active, mild-to-moderate UC.