Polarized Raman spectroscopy was used to determine the crystal orientation in uniaxially oriented fibers of poly(ethylene terephthalate) (PET). The Raman tensor ratios and the second-(P-2) and fourth-order (P-4) Legendre polynomials of the orientation distribution function of the 998 cm(-1) vibrational band are reported. We show that both P-2 and P-4 for this band increase more rapidly than the average chain orientation as determined by birefringence. In addition, they reach plateau values Of P-2 = 0.90 +/- 0.06 and P-4 = 0.55 +/- 0.09 for birefringence values >0.05 in our drawn and annealed samples. Since this band has been assigned to the all-trans conformation of the glycol unit, we suggest that these P-2 and P-4 values correspond to the orientation of the crystalline units. This is the first time that the orientation parameters of the crystals of PET as determined by polarized Raman spectroscopy have been reported.