Hydroxyapatite is the most widely accepted biomaterial for the repair and reconstruction of bone tissue defects. It has all the characteristic features of biomaterials, such as, biocompatible, bioactive, osteoconductive, non-toxic, non- inflammatory and non-immunogenic properties. In this book, the authors present current research in the study of the synthesis, properties and applications of hydroxyapatites. Topics discussed include nanodimensional and nanocrystalline hydroxyapatite and other calcium orthophosphates; application of biomimetic nanocrystalline apatites in drug delivery and tissue engineering; polymer matrix mediated synthesis of nano hydroxyapatite crystals; osteointegration of titanium porous implants with carbon nanocoating and hydroxyapatite particles into the pores; hydroxyapatite thin film prepared by sputtering technique for medical applications; and hydroxyapatite application in dentistry and maxillofacial surgery.