Carbon nanotubes (CNTs) exhibit excellent electrical conductivity, mechanical strength, stiffness and toughness as well as good biocompatibility with human cells. Accordingly, CNTs are attractive reinforcing materials for polymer nanocomposites designed for orthopedic applications. The integration of CNTs into polymeric materials opens up new frontiers in biomaterials. In this chapter, the synthesis, purification and functionalization of carbon nanotubes, mechanical property and biocompatibility of CNT-polymer nanocomposites are described in details. Proper understanding of the process-structure-property relationship of CNT-polymer nanocomposites is necessary to achieve desired mechanical property and biocompatibility.