Composites based on polymers and ceramics are being developed with the aim to improve tissue interaction. These scaffolds can locally release growth factors or antibiotics and enhance bone ingrowth to treat bone defects and even support wound healing. The composite systems combining advantages of polymers and ceramics seem to be a promising choice for bone tissue engineering. DNA is one of the most promising biopolymers at the forefront of the emerging clinical and medical applications because of the genetic material. In addition, the DNA molecules are covered with inorganic minerals; in the process of biomineralization, they might form bioactive nanocomposites that could be regulated. The DNA/HA nanocomposites are expected to be available for bone tissue engineering and pave the way for a new inorganic carrier in gene therapy. In this study, the hydroxyapatite(HA) formation on the surface of DNA molecules in simulated body fluid(SBF) was examined. The osteoconductivity is estimated using SBF having ion concentrations approximately equal to those of human blood plasma. After immersion for 4 weeks in SBF at 36.5 °C, the HA crystallites possessing 1-14 micrometer in diameter grew on the surface of DNA molecules. The leaf flake-like and spherical shapes morphologies were observed through scanning electron microscopy analysis. Original peaks of both of DNA and HA were characterized by fourier transform infrared spectroscopy. The Ca/P ratio(1.1-1.5) in HA was estimated by energy dispersive X-ray analysis. After biomineralization, the calculated weight ratio of DNA/HA was 18/82 by thermogravimetry/differential thermal analysis. The molecular orbital computer simulation has been used to probe the interaction of DNA with two charge-balancing ions, CaOH+ and CaH2PO4+. The adsorption enthalpy of the two ions on DNA having negative value was the evidence for the interface in mineralization of HA in SBF. The results of toxicity assay of DNA/HA nanocomposites were discussed.