The specific etiologies of ulcerative colitis are unknown, but ongoing laboratory and clinical research is leading to holistic concepts of disease pathogenesis. At present, it is hypothesized that immune stimulation by gut lumenal antigens, defects of the gut mucosal barrier, immune regulatory disturbances, generation of pro-inflammatory mediators, and other gut physiologic factors all contribute to the development of idiopathic inflammatory bowel diseases in genetically susceptible individuals. This review presents the past year's progress in investigations on the pathogenesis of and medical-surgical treatment interventions for ulcerative colitis.