Bone is a dynamic, highly vascularized tissue with a unique capacity to heal and remodel without leaving a scar. Its main roles are to provide structural support for the body, serves as a mineral reservoir, and it protect the internal organs. Hence, it is logical to say that major alterations in its structure due to injury or disease can dramatically alter one’s body equilibrium and quality of life. In this thesis, types of bone grafts and bone substitutes were investigated, each type with its properties, advantages, and disadvantages. Hydroxyapatite [Ca10(PO4)6(OH)2; abbreviated to HAp] is an inorganic compound whose chemical composition is similar to the composition of the bone and it is used in biomedical applications as a bone substitute material in orthopedics and dentistry. The first part of the experimental work of the thesis includes preparation of hydroxyapatite chemically by two precipitation methods; the first method consists of addition of H3PO4 to a suspension of Ca(OH)2 and and the second method consists of the addition of (NH4)2HPO4 to Ca(NO3)2.The second part of the practical work includes extraction of natural hydroxyapatite from bovine’s femur bone by using thermal decomposition method. X-ray diffraction analysis, Fourier transforms infrared spectroscopy, particle size analyzer, and atomic absorption analysis were applied to test the chemical and physical characteristics of the resulting product. Results of the first precipitation method indicated that the resulting powder was hydroxyapatite, while the second method resulted in formation of tricalcium phosphate which is another type of bone substitutes. For the extraction part, the results showed that the extracted white powder was pure hydroxyapatite and did not contain any other organic components of the bone.