Chitosan is an important kind of biomaterial that is widely used in medical applications. One of the key concerns about its use is the preparation of composites used for bone engineering. Aim of this study concerns the preparation of three-dimensional nanocomposites having potential use in bone repair and regeneration. The magnetite/hydroxyapatite/chitosan nanocomposites were prepared via in situ compositing method by preparing precursor solutions and molds with chitosan membrane. These nanocomposites were characterized by chemical, spectroscopic, magnetic, and morphological methods. X-ray diffraction analysis results demonstrate the formation of magnetite and hydroxyapatite in the chitosan matrix. FTIR analysis indicates that inorganic nanoparticles were chemically bound to the amino and hydroxyl groups in CS molecules. From TG/DTA data, it can be concluded that during preparation raw materials were almost perfectly incorporated into the nanocomposites, and the decrease in decomposition temperatures indicates the formation of chemical bonds between inorganic nanoparticles and chitosan molecules. TEM results show that the maximum size of inorganic particles in the magnetite /hydroxyapatite/chitosan nanocomposites was under 50 nm, and these particles were dispersed homogeneously in the chitosan matrix. From the magnetic measurement, it could be concluded that the nanocomposites were superparamagnetic, which is also the peculiarity of nanomagnetites. (c) 2008 Wiley Periodicals, Inc.