This book is designed as a comprehensive, useful, up-to-date presenta tion of computed tomography (CT) of the major disease states involving the gastrointestinal tract, mesentery and peritoneal cavity. Rather than representing one institution's sole experience, the coverage reflects masterful contributions from international centers with the most exten sive experience. Plain £lm identification of intraperitoneal structures is generally lim ited to those aspects outlined by contrasting extraperitoneal fat or naturally occurring intraluminal gas. Routine contrast studies of the intestinal tract permit visualization of its internal mucosal contour alone. An outstanding limitation has been the inability to accurately evaluate the thickness of the bowel wall. In these circumstances, only indirect signs are relied upon for the radiologic diagnosis of mural or serosal disease. Approaches to visualize the bowel wall and perito neal reflections by the introduction of intraperitoneal contrast medium have been of only limited success (1-3). Computed tomography, by virtue of its superior density discrimination and excellent spatial resolu tion, permits exquisite imaging of the gastrointestinal tract, mesenter ies and peritoneal cavity. In the presentation of normal and pathologic anatomy and the discus sion of clinical efficacy, efforts have been made to keep the text as precise as possible. In the elaboration of CT's capability to detect and to determine the extent of disease, particularly as the findings relate to staging, insights and responsible conclusions are drawn for the accuracy, relia bility, limitations and sources of error for the study.