In this work we present the features and the properties of natural and synthetic apatites, which we use in an experimental study of various commercial products composed by calcium phosphate. After having considered the general concepts of biomaterials and biocompatibility, we describe non biological tests used for the characterization of these products. Biomaterials used in this study are: reabsorbable Dac Blu, non reabsorbable Dac Blu, non reabsorbable atomized Dac Blu, non reabsorbable thin Dac Blu, reabsorbable Biocoral 450, Calcitite 2040-12, Orthogel, Apagen, BTF 65, Calcitite 4060-2 Osprogel, Bio-oss, Biostite, Osprovit, Merck Hydroxiapatite. Tests used are: X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric and thermodifferential analysis (TG, DTG, DTA), scanner-ing electron microscopy (SEM) morphological analysis. Last but not least, we underline the particular features of these tests whose interpretation allows a more precise definition of the bioactivity of a biocompatible material.