Nanophase alpha-alumina and hydroxyapatite (HA) composites with and without CaF(2) were prepared and sintered at 1100 degrees C for 1 h to investigate their densification, structural and biocompatibility properties. X-ray diffraction method was performed to examine the second phases in the materials. It was observed that HA slightly decomposed into tricalcium phosphate and CaO with the addition of CaF(2). The addition of CaF(2) also resulted in an increase in the density of the composites. The composites were then evaluated for their biocompatibility using cytotoxicity tests. Saos-2 cells were seeded on composite discs in order to investigate the cellular responses to materials in terms of morphology, attachment and proliferation using scanning electron microscopy and 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyl-2H-tetrazolium-bromide viability assays. Cell culture studies showed that the nano-alumina and HA composite discs with or without CaF(2) additions were biocompatible. CaF(2) addition into the composites improved cell attachment and proliferation after 3 days of culture.