Hydroxyapatite nanoparticles are tiny nanoparticles with a 20-80nm diameter with spherical/faceted high surface area. These nanoparticles are very crucial for research purposes and in the field of biosciences. It resembles bone apatite as it has a hexagonal structure and a stoichiometric ratio of 1.67. Hydroxyapatite is an important compound of calcium because it is stable as compared to other calcium compounds. Hydroxyapatite nanoparticles are widely being used in the field of medical science where it is used as a biomaterial for use in prosthetic applications. It is also used to prepare hydroxyapatite bioceramic that has a variety of applications such as bone tissue engineering, dental surgery, traumatology, orthopedic & dental implant coating, pulp capping, desensitizing agent after teeth bleaching, periodontal defects treatment, and remineralizing agent in toothpaste. Research is also being conducted to use hydroxyapatite nanoparticles in the treatment of tumor-associated bone segmental defects. These nanoparticles are available for research and commercial purposes with miraculous 99.99% purity.