This book evolved from a two-day 1993 International Symposium on Radiation and the Gastrointestinal Tract held at the Uniformed Services University of the Health Sciences, Bethesda, Maryland. This area of investigation is particularly important because of growing medical needs and the documented occurrence of accidents involving overexposure of healthy subjects/patients. Some questions have been answered through cellular and animal research-results that lead to hypotheses that have been tested through clinical protocols. In an attempt to answer the unresolved questions, basic scientists and clinicians describe the data obtained to date, present in a critical manner the consensus that has been reached, and discuss what still remains to be investigated. The book is divided into five parts: Overview and Clinical Perspective, Emesis, Motility, Diarrhea, and Behavioral Correlates of Gastrointestinal Dysfunction. Each part consists of separate discussions on the pathophysiology, the methodology, and, when applicable, the clinical relevance of the observations. The book provides helpful information to both basic scientists involved in radiobiological research and to clinicians caring for patients exposed to radiation. It also serves as an introduction to the subject for young clinical investigators interested in the field and for scientists searching for correlates between their observations and disorders of the gastrointestinal tract.