Structural changes occurring during a stretching process have been studied with the uniaxially and biaxially drawn PTMT films. The stress-induced crystallization has been observed from the stress-strain curve showing abrupt increase of stress at a specific draw ratio (dr = 2.5) at which the density was found to increase significantly with the draw ratio. This stress-induced crystallization phenomenon was also confirmed with the decreased crystallization enthalpy and increased glass transition temperature approximately at dr = 2.5. The refractive indices along three principal directions were also measured with the polarized refractometer. It was found that for the uniaxially drawn films the refractive index along the deformation direction showed fast increase at the onset of stress-induced crystallization. Using double-edged ATR crystal and rotatable sample holder, the orientation parameters of several infrared bands along three spatial directions of PTMT films were obtained with the polarized FTIR-ATR spectroscopy. By normalizing absorbances of all infrared bands studied in this work with absorbance of the reference band at 1410 cm(-1), followed by multiplying the absorbance of TM polarization with the theoretical effective thickness ratio between two polarizations, i.e., d(e)(TE)/d(e)(TM), attenuation indices in three principal directions were found to be very close to each other for samples prior to drawing. In general, attenuation indices along the deformation directions increased with the increasing function of draw ratio for the bands of which transition moments are parallel to the chain direction. The fact that the attenuation index of the band at 1358 cm(-1) showed an abrupt increase at dr = 2.5 indicates that this band is preferentially affected by the trans conformers in the crystalline region. All three attenuation indices of the 1385 cm(-1) band that corresponds to the CH2 wagging mode of gauche conformers showed a gradual decrease with the draw ratio, probably due to the conformation change upon stress-induced crystallization. The orientation parameters along the deformation directions of the C-O stretching band at 1040 cm(-1) increased almost continuously without sudden jump at the onset of stress-induced crystallization.