In this paper, we investigate the orientation behavior of impact modified PET. Core-shell particles, a metallocene polyethylene (mPE) and glycidyl methacrylate modified mPE (gmPE) were blended with PET using single screw extrusion. Morphology, crystallinity, orientation development and mechanical properties of oriented blends were studied following different orientation conditions. It was observed that core-shell impact modifier added to PET does not affectits orientation behavior and that the particles do not deform. Non-reactive mixing with mPE does not affect the orientation developed in PET for the same draw ratio, but the stress levels are affected (higher) due to an earlier crystallization of PET. Reactive blending with gmPE enhances the orientation of PET and the stress levels when orienting are higher than for pure PET, due to an earlier crystallization of PET and strain hardening of mPE being oriented, which indicate a good adhesion at the interface. The elongation at break is affected positively in many cases with the addition of a modifier, particularly gmPE, which is an indication of an improved toughness.