The synthetic hydroxyapatite is a very useful material for numerous applications in medicine as a biomaterial. One of the most economic manufacturing process is the precipitation route. In the present work, synthetic hydroxyapatite was prepared using the precipitation route, starting with aqueous solutions of calcium nitrate (Ca(NO3).4H2O ) and ammonium phosphate (H2(PO4)NH4). The effects of physical-chemical variables such as pH, temperature, time of agitation, ageing time and heat treatment of the mixture were evaluated. The characterization of the samples obtained in different conditions made possible to conclude about the optimal values of the studied variables for the synthesis of this material in laboratory conditions.