In this study, doping of aluminum (Al3+) and/or fluoride (F-) ions into tri-calcium phosphate (TCP)-hydroxyapatite (HA) composites at various compositions were performed to investigate their microstructure and mechanical properties. Composites were synthesized by a precipitation method and sintered at 1100 degrees C for 1 hr and 5 hrs. Densities of the sintered materials were increased by extending the sintering time and increasing the amount of Al3+ and F- doping. beta-TCP was observed as the main phase in the composites by Rietveld refinement method. Moreover, considerable amount of HA was detected in the composites. Lattice parameters decreased upon ions substitution. Addition of doping ions resulted in smaller grains. In general, presence of Al3+ ions in the composites had negative effects on mechanical properties of the samples while substitution of the F- ions improved that of the samples.