The effect of the addition of 2-8% by weight of commercial atactic polystyrene to fibergrade polypropylene on the drawability of the multifilament yarn spun from the blends and on the mechanical properties and thermal shrinkage of the drawn yarns was studied. In the as-spun state, polystyrene is present in the form of near-spherical particles and improves the drawability and plastic deformation characteristics of the yarn. In the drawn state, with higher molecular orientation and more compact structure, the intrinsic rigidity of the polystyrene molecule manifests itself in the form of enhanced stiffness and greater creep resistance.