It has been shown that the polymer matrix promotes a good utilization of fibers elastic and strength properties in composites. Researches to estimate the utilization of the noted properties of the carbon fibers in the composites with the carbon matrix have been studied. They have been carried out with two types of carbon-carbon composites. The first one had a mutually orthogonal arrangement of the reinforcements in the axial direction. The carbon-carbon composite of the second type was a transversal-isotropic material reinforced in the axial direction. It had a complex structure with so-called star-like reinforcement lying in the plane. Its fibers were located in three directions (0+60) in the main plain of reinforcement (in the plane) and perpendicular to it, in the direction. The two types of this material were examined. They had differences in the diameter of reinforcement and in the density of composite. The tensile, compression and shearing of the selected material were tested. The received experimental data of their elastic and strength characteristics were compared with their calculated values. It has been shown that the impact of the replacement of the polymer matrix to the carbon matrix on the elastic modules values of the examined composites has not been significant. At the same time it replacement not only significantly reduces the degree of utilization of the carbon’s fibers ultimate strength in composites, but also has a significant negative influence on their shearing characteristics. It has been noted that the possible reason of that is the presence of defects in the carbon matrix and the lack of its adhesive bond with fibers. The lowest degree of utilization of the reinforcing fibers strength properties in the examined composites is the case with the tensile loading. The ultimate strength of the examined carbon-carbon composites in the case of tensile doesn’t exceed 24% of their reinforcing fibers ultimate strength. The composite material with the complex scheme of the reinforcement has shown higher sensitivity to the indicated matrix replacement than the orthogonal reinforced.