Budesonide is a corticosteroid characterized by high topical activity and low systemic effect associated with fewer glucocorticoid-related adverse events than conventional steroids. Differently from Crohn's disease, no evidence suggests that oral budesonide is effective for the induction of remission of ulcerative colitis (UC). Budesonide multi-matrix (MMX) system is a new oral preparation that, by employing a MMX, provides the release of the drug throughout the entire colon. Its efficacy in inducing UC remission, at a dose of 9 mg, is based on some recent trials. However, in two studies the absolute differences between budesonide MMX and placebo were much lower than the rate of success reported in previous trials with mesalazines. In addition, the therapeutic advantage of budesonide MMX 9 mg over 5-aminosalicylic acid (5-ASA) showed by one study, and the advantage of budesonide MMX over budesonide reported in the other study, was only 5.8 and 4.8%, respectively. The evidence supporting the use of budesonide MMX at a dose of 6 mg for maintenance is weak. Therefore, the effective dosage should be 9 mg also in maintenance, but not for > 4 - 6 months, because a prolonged treatment has showed to increase the rate of side effects.