There is a growing body of experimental and clinical data to suggest that the organs of the digestive system may be subjected to considerable oxidative stress associated with acute and chronic inflammation. Although inflammation and ischemia play a key role in producing oxygen-derived free radicals in the digestive tract, the contribution of other factors, such as transition metal imbalances, lipid and glucose metabolic disturbance, and the interaction with gaseous molecules including nitric oxide and carbon monoxide, has also been suggested. Recent studies have demonstrated that several biomarkers indicating oxidative stress-mediated damage may help in monitoring the degree of disease and planning the design of new therapeutic strategies. In addition, recent advances in ‘omics’ research (genomics, proteomics, metabolomics, etc.) may bring a breakthrough in the field of gastroenterology and hepatology: Several molecular targets for oxidative stress have been presented by the ‘omics’. This book includes up-to-date reviews on the relevant issues in free radical biology in a combination with expert basic research reviews and clinical aspects in gastroenterology and hepatology. Providing information about new molecular targets for the treatment or prevention of digestive diseases, this book should be read by clinical and basic researchers in gastroenterology and hepatology.