The book "Medical Imaging and Augmented Reality" documents the results of the 4th International Workshop on Medical Imaging and Augmented Reality, which took place in 2008 at the University of Tokyo. It provides a comprehensive overview of the latest developments in medical imaging and its integration into therapeutic and interventional procedures. The contributions come from leading researchers in the field and reflect the rapid advancements in technology that are revolutionizing medical practice. The focus is on the connection between life sciences, medicine, physics, and engineering to optimize diagnostic and therapeutic processes. The quality of the submitted works was remarkable, highlighting the relevance and impact of the workshop on research in these areas. The book is a valuable resource for professionals and students who wish to engage with the latest trends and technologies in medical imaging and augmented reality.