SOMASIF ME C16, a filler that enables generation of anisotropic nanoparticles by in situ exfoliation of organic layered silicates, was melt compounded with poly(propylene) (PP) in the presence of maleic anhydride-grafted PP. Fibers were prepared from this composite by a spinning procedure. The prepared anisotropic fibers were partially oriented by using different drawing ratios. The morphological study showed that the drawing ratio of the fibers particularly influences the level of exfoliation of the SOMASIF ME C16 where the nanoparticles are formed. The layered sheets of the SOMASIF particles are oriented in the direction of the fiber axis. The tensile strength of the filled fibers increases with the increase of drawing ratio much more than that of unfilled PP fibers. This result is accounted for by the formation of exfoliated structures from the nanoparticles of SOMASIF ME C16 by fiber drawing. (C) 2003 Wiley Periodicals, Inc.