The effect of repetitive processing on the mechanical properties and fracture toughness of dynamically vulcanized isotactic polypropylene/ethylene-propylenediene rubber blends (TPVs) with and without addition of beta-nucleating agent (beta-NA) was studied. The results showed that the repetitive processing did not cause much loss in the mechanical properties of TPVs, especially for TPVs with beta-NA, and TPVs with beta-NA showed better performance stability than TPVs without beta-NA. Essential work of fracture (EWF) approach was used to study the fracture behavior, and the results showed that the value of w(e) (the specific essential work of fracture) of TPVs without beta-NA showed a significant decrease while that of TPVs with beta-NA almost kept constant after repetitive processing. Differential scanning calorimetry and wide-angle X-ray diffraction were used to study the variation of crystalline structures, and the results indicated that the repetitive processing showed no significant influence on the crystalline structures of TPVs, and the beta-NA maintained high-nucleating efficiency after repetitive processing. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 120: 86-94, 2011