The orientation of poly(ethylene naphthalene-2,6-dicarboxylate) (PEN) films with different morphologies were studied by wide-angle X-ray diffraction. Different structures were obtained by thermally treating biaxially stretched PEN samples. Virgin and thermally treated (I h at 240, 250, and 260degreesC) samples of PEN bioriented films were characterized by DSC to determine the glass-transition temperature and the crystallinity ratio. To define the orientation of crystallites in the 25 mum thick bioriented samples, pole figures were recorded for various PEN samples, as a function of their position in the transverse drawing direction. The significant result is that there is a dominant crystal population, whose c-axis direction varies from +45degrees at one sample edge to -45degrees at the other edge, the orientation at the center being parallel to the transverse direction. There is also a secondary population, which can be seen only near the center. DSC studies also showed that by increasing the annealing temperature the crystallinity ratio was increased and pole figures showed that the texture was modified, probably because of disorientation mainly from an annealing temperature of 260degreesC. (C) 2003 Wiley Periodicals, Inc.