The results of investigation of the surface physical and chemical properties of polylactic acid, hydroxyapatite and a composite material based on them taken in the ratio of components 80/20, modified by carbon ions with exposure doses of 1 × 1015 and 1 × 1016 ion/cm2 at an accelerating voltage of 20 kV are presented. The surface chemical composition of the samples is studied by Fourier transform infrared spectroscopy. The elemental composition of the surface is studied by X-ray photoelectron spectroscopy. According to the obtained results, the simultaneous processes of destruction and cross linking of polylactic acid and polymer macromolecules are established. To assess the wettability of the untreated and modified surface of materials, contact-angle measurements and surface energy calculations are performed. It is established that carbon-ion implantation leads to improvement in the hydrophobic properties of materials; this process is accompanied by a decrease in the free surface energy.