Bioactive nanocomposite of nonstoichiometric apatite (ns-AP) and poly(epsilon-caprolactone) (PCL) was synthesized and its porous scaffold was fabricated. The results show that the hydrophilicity and cell attachment ratio on the composite surface improved with the increase of ns-AP content in PCL. The composite scaffolds with 60 wt % ns-AP content contained open and interconnected pores ranging in size from 200 to 500 pm and exhibit a porosity of around 80%. In addition, proliferation of MG(63) cells on the composite scaffolds significantly increased with the increase of ns-AP content, and the level of alkaline phosphatase (ALP) activity and nitric oxide (NO) production of the cells cultured on the composite scaffold were higher than that of PCL at 7 days, revealing that the composite scaffolds had excellent in vitro biocompatibility and bioactivity. The composite scaffolds were implanted into rabbit mandible defects, the results suggest that the introduction of ns-AP into PCL enhanced the efficiency of new bone formation, and the ns-AP/PCL composite exhibited in vivo good biocompatibility and osteogenesis. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 116: 762-770, 2010