A series of blends of poly(trimethylene terephthalate) (PTT) with ethylene-propylene-diene copolymer grafted with maleic anhydride (EPDM-g-MA) were prepared in composition by weight 95/5, 90/10, 80/20, and 70/30. Their morphologies, crystallization behavior, and mechanical properties were investigated. Morphology observation shows the well-dispersed domains of EPDM-g-MA in PTT matrix with weight-average particle size from 0.98 to 3.64 mu m when the EPDM-g-MA content increases from 5% to 30% (mass fraction) in the blends. The constancy of the crystallinity level indicates that the elastomeric phase does not disturb the crystallization process of PTT. The addition of rubbery EPDM-g-MA to PTT matrix increases the notched Izod impact strength, but impairs the tensile strength properties. POLYM. ENG. SCI., 50:624-628, 2010. (C) 2009 Society of Plastics Engineers