Due to a great chemical similarity with the biological calcified tissues, many calcium orthophosphates possess remarkable biocompatibility and bioactivity. Materials scientists use this property extensively to construct artificial bone grafts that are either entirely made of or only surface-coated with the biologically relevant calcium orthophosphates. Porous scaffolds made of calcium orthophosphates are very promising tools for tissue engineering applications. A comprehensive overview of calcium orthophosphates, this book highlights their importance and biomedical uses.