Nanotechnologies have the potential to improve current disease diagnosis due to their ability to circulate in the blood and distribute in the body to image tissues and cells or therapeutical applications to deliver a payload. Among nanoparticles with different materials composition, inorganic nanoparticles composed of calcium phosphate have numerous advantages including ease of synthesis, control of physico-chemical properties, strong interactions with their payload, and biocompatibility. In this review we discuss the different routes of synthesis of calcium phosphate nanoparticles, novel systems, strategies to load agents, biostability and cytotoxicity, biodistribution and pharmacokinetics, bio-imaging and therapeutical applications.