The structural parameters and strength properties of a new generation of polyacrylonitrile fibers have been analyzed. These fibers, after being carbonized, can be used in biomaterial engineering. They are characterized by a high tensile strength of 31-43 cN/tex. An advantageous influence of nanoparticles added to the fiber matter on the degree of crystallinity has been found. When nano-particles of hydroxyapatite are incorporated into these fibers, their degree of crystallinity increases by about 5%. (c) 2006 Wiley Periodicals, Inc.