The project aimed at deposition onto the carbon-carbon composites substrates of surface layers made of various carbon modifications with properties governed by their structure, characterization of engineering, physical and chemical properties of the layers and substrates, and investigation of the influence of important properties on the layer biocompatibility by measuring cell adhesion, proliferation and other features. Carbon-carbon composites coated with amorphous carbon (a:C-H), pyrolytic carbon (deposited at 850C or 1900C), titanium-carbon (Ti:C), or chromium-carbon (Cr:C) layers were employed for biocompatibility tests in vitro. To pursue interaction of the composites with vascular smooth muscle cells, and human osteosarcoma-derived MG63 cells were studied. Coating with pyrolytic carbon and with Ti:C layer proved to be most stable from the viewpoint of releasing particles of carbon substrate or the surface layer, as well as of cell adhesion and proliferation. The influence of surface roughness of the pyrolytic carbon coating on the mentioned cell adhesion and proliferation was investigated in detail. The results have revealed that surface treatment of carbon-carbon composites is a promising way to improve their implementation to medicine. Coating of the composites with pyrolytic carbon is most suitable especially if supplemented with grinding and polishing.