Ulcerative colitis and Crohn's disease, collectively termed inflammatory bowel disease (IBD), are complex disorders because of their wide variations in clinical manifestations. These two disorders constitute multi-system diseases of idiopathic origin. Both are found world-wide and spare no socioeconomic group. Recent scientific and technological advances have, not only led to greater understanding of the pathogenesis underlying these disorders, but have also enabled us to make a correct diagnosis in the earlier stage and to use better and more efficacious medical therapies for these two diseases. Dr. Zheng from China has experience in the research and treatment environment for IBD at the University of Chicago in the U.S.A. He completed his doctoral work in Nutrition at Tufts University and has been an active gastroenterologist in the diagnosis and management of gastrointestinal disease, in particular IBD, in China. Thus, he is well suited to the task of bringing together this information for IBD. In this handbook, a highly distinguished group of doctors and professors have been invited to present an updated knowledge of current status as related to the diagnosis and medical therapy of IBD. These articles highlight many advances to date with their clinical experiences. Thus, this handbook will greatly increase recognition of the complexity of these conditions in clinical practice, and enhance the experiences of management with IBD patients.