One of the characteristics to be achieved by biomaterials is to have similarity to the host material. Carbonated hydroxyapatite (HAC) has both considerable composition and order of magnitude in relation to human bone. For the application in cases of bone substitution, HAC would be a good candidate, but it is shown with low mechanical resistance, which would make it difficult to apply it in areas that perform high mechanical stress. However, carbon nanotubes (CNTs) have low density and strong covalent bonding between their atoms, which confers high mechanical resistance to the material. For this reason, the influence of CNTs on the structure and properties of HAC was studied. Pure CNTs (pristines) and functionalized with CNT-COOH carboxyl were inserted for the study. The results of Elemental Analysis (CHN-O) indicated the amount of carbon present in the samples in each case. The results of XRD, TG / DTA and IR showed that pristine CNTs apparently did not significantly influence the structure of HAC. However, XRD results suggested that CNTs functionalized with COOH clusters may have interacted with HAC. In this case, the displacement of some peaks was observed in the sample (HAC + CNT_COOH), showing a decrease in the c axis of the sample. The refinement of the diffractograms also revealed samples of the nanometric order, with crystallite size in the order 25 Å. The results of the thermal analysis showed a peak close to 600 ° C, associated to the decomposition of the carbonate; Indicating the presence of these ions in the A site of HAC. The IR spectra showed the vibrational modes corresponding to the carbonate ion, confirming the presence of these ions in sites A and B.