This article presents the results of the experimental study on manufacturing and mechanical evaluation of poly(L-lactide-co-glycolide) (PLGA)-based fibers modified with ceramic nanoparticles. Study was conducted to establish the effect of biomimetic formation of apatite layers on polymeric fibers on their mechanical properties. The tensile tests were performed to determine the influence of polymer crystallinity and the presence of hydroxyapatite nanoparticles (nanoHAp) on mechanical properties of PLGA fibers coated with hydroxyapatite (HAp) layer. HAp deposits on the surfaces of the fibers precipitated from simulated body fluid (SBF). Three types of fibers coated with HAp layers were compared in mechanical tests. The results indicated that by using a biomimetic fiber coating method the mechanical properties of the fibers are affected by their crystallinity. The nanoHAp modified polymer fibers after incubation in SBF were found to have a continuous HAp layer. The layer affected the mechanical behavior (force-strain function) of the fibers from nonlinear to linear, typical of ceramic materials. The tensile modulus of the fibers with a continuous layer was found to increase with the apatite layer thickness, whereas the tensile strength decreases. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 3702-3709, 2011