1 A colonic delivery system is described to deliver orally ingested drugs to the colon and release them at that site by coating with an acrylic based resin (Eudragit S). The technique is validated using X-ray evidence and serum levels of a convenient marker, sulphapyridine. 2 This colonic delivery system is particularly suitable for drugs such as 5-amino salicylic acid or steroids in the management of patients with colitis.