This book aims to introduce the latest research in gut microbiota by systematically summarizing how it modulates the pathogenesis of organ injury including alimentary tract injury, liver injury, lung injury, brain injury, renal injury, heart and vascular injury, endocrine disorders, immune responses and multiple organ dysfunction syndrome (MODS) during sepsis. Gut microbiota which is recognized as a new “organ” in the body has been demonstrated to be able to regulate the homeostasis of many organs. The key role played by gut microbiota is the hotspot in biomedical research nowadays. This book provides a state-of-the-art report on recent discoveries regarding the novel insight into the mechanisms of human diseases progression. It will also offer the overall picture of the pathophysiologic roles of gut microbiota. This book is helpful for graduate students and professional researchers to get the knowledge of frontiers in both gut microbiota and organ injury.