The skeletal system is important to the body both biomechanically and metabolically. It maintains the shape of the body; protects soft tissues; transmits the force of muscular contraction during movement. Bone is a protective and production site for bone marrow, which is a blood-forming system. It is a mineral reservoir which regulates the mineral homeostasis in the circulating body fluids. This book studies bone morphology, composition, mechanics, cells, orthopedics biomaterials and their generations: bioinert (1st generation), bioactive and biodegradable (2nd generation), and designed to stimulate specific cellular responses at the molecular level (3rd generation), as well as the bone graft materials with their orthopedic applications. Using nanotechnology to fabricate these biomaterials as a (MWCNTs) (0.5,1,1.5) %wt, and nanoparticles (HA) (2,3,4) %wt, dispersed respectively in (PMMA), with the use of mixing and vacuum technique; many useful results were obtained in different mechanical and physical inspections done in vitro like (porosity, topography, simple tension, compression, microhardness, and fatigue) while these inspections were carried out under the body conditions.