The mechanical properties of electrospun fibers are influenced by crystallinity and molecular orientation, and their crystal structure is controlled by the processing parameters and the electrical and rheological properties of the polymer solution. The auxiliary electrode has been widely used as a stabilizing tool in the electrospinning process, and in this study, the effect of the auxiliary electrode on the crystalline morphology or molecular orientation of spun fibers was investigated with respect to structural formation in the elongational region of the initial spun solution. (C) 2008 American Institute of Physics.