The purpose of this study was to demonstrate that mesalazine 4g orally per day once daily (QD) is non-inferior to the reference regimen, mesalazine 4g per day in two divided doses (BID) (2g x 2 per day), in patients with active ulcerative colitis (UC) treated for 8 weeks, in terms of remission evaluated with the Ulcerative Colitis Disease Activity Index (UC-DAI) score and defined as less than or equal to 1. Both groups (4g QD and 2gx2) received an enema containing 1g of mesalazine at bedtime during the initial 4 weeks.