This will be a multicentre, randomised, double-blind, double-dummy, parallel group comparative study in patients with mild or moderate, active ulcerative colitis. The study will compare budesonide-MMX™ 6 mg and budesonide-MMX™ 9 mg tablets to placebo and to Entocort® 3 x 3 mg capsules, in four parallel groups of patients over an 8 week treatment period.