This book, the proceedings of Falk Symposium No. 123, VI International Symposium on Inflammatory Bowel Diseases, held in Istanbul, Turkey, on September 3-5, 2001, focuses on the issues and controversies pertinent to IBD in the 21st century. The achievements in medical, surgical, and in the basic sciences in the last twenty years since the first Jerusalem IBD Symposium are summarized in detail. Controversies with respect to the medical treatment of inflammatory bowel diseases are discussed. One section deals with surgical issues such as laparoscopic surgery in inflammatory bowel diseases, ileo-anal pouches and the surgical treatment of Crohn's disease. The last section is devoted to the biological treatment of IBD and to the needs both in medical science and in the clinic.