This book focuses on hyperbaric oxygenation (HBO) therapy from the molecular biology perspective and its clinical applications, including molecular mechanisms of HBO's positive effect on cellular function in hypoxic tissues. HBO is a therapeutic tool that enhances oxygen supply to hypoxic tissues and improves wound healing/tissue remodeling. Currently HBO therapy is applied to a wide range of clinical cases, which include not only acute hypoxic diseases but also many chronic and refractory diseases involving tissue hypoxia or intractable infection. HBO therapy is a well-recognized regimen for many researchers and clinicians. The first half of the book outlines basic molecular mechanisms of HBO and their potential applications for clinical activities, while the second half describes the rationale behind introducing HBO therapy into suitable clinical cases and presents successful clinical reports. It is primarily written for HBO clinicians, physiologists and basic research scientists, but is also of interest to clinicians who have an interest in this field considering introducing HBO therapy.