AbstractDetermination of the orientational order of morphological components in polyethylene terephthalate (PET) is sought through quantitative application of two‐dimensional rotor synchronized magic angle spinning (ROSMAS)13C NMR technique. Previous study in our laboratories had established a procedure for resolution of the carbonyl carbon (CA) and glycol ethylene carbon (GE) resonances into those corresponding to four morphological components.1Due to paucity of sidebands in the GE resonances, the focus has been on the CA resonances in this attempt to obtain orientation distributions. A set of PET fibers possessing a broad range of crystalline and orientational order has been used to infer the meaning of NMR‐based orientation measurements vis‐a‐vis other techniques. A surprising finding of this study is the observation that the orientational orders of the broad component in the13C CP/MAS spectrum and the narrow component are very similar in these fibers. ©1995 John Wiley&S