This book is the proceedings of the Falk Symposium No. 135 held in Prague, Czech Republic, on September 12-13, 2003, and is dedicated to the important issue of immunological aspects of diseases of the liver and gut. Without any doubt, immunological pathways are among the most important and universal factors in the pathogenesis of all diseases. Their importance is also constantly increasing, because these principles have been adopted in clinical practice for both diagnostic and therapeutic procedures. Chapters by prominent experts will stimulate new ideas and set the scene for productive discussion on this topic.