Carbon nanotubes (CNTs)/hydroxyapatite (HA) nanocomposites with ferromagnetic properties have been fabricated via an in situ process in which a HA-based matrix was used as the catalyst for the growth of CNTs in a chemical vapor deposition system. The results showed that approximately 20 wt% of multi-walled CNTs with a mean diameter of 40-60 nm have been produced in the nanocomposites. The CNTs in the nanocomposites were observed to have an undamaged structure, with ordered graphitic layers and non-defective lattice structure on their walls. The growth of CNTs are shown to be in situ from the nano-HA crystallites. The compress mechanical properties of these CNTs/HA composites prepared by this method were significantly better than that of the composites prepared by physical mixing CNTs with HA particles. Magnetic measurement showed that the nanocomposites exhibit a ferromagnetic behavior with a saturation magnetization of 0.126 emu g(-1) at a room temperature. These magnetic nanocomposites could have a potential application in the drug delivery system as well as other biomedical fields. (c) 2012 Elsevier B.V. All rights reserved.