Thermoplastic elastomers (TPEs) based on dynamically cured epoxidized natural rubber/high-density polyethylene (ENR/HDPE) blends were prepared. Influence of the process oil, blend proportion, and curing systems were investigated. It was found that the oil-extended thermoplastic vulcanizates (TPVs) exhibited better elastomeric properties and improved ease of the injection process. Increasing the proportion of ENR caused increasing elastic response of elongation at break, tension set properties, and tan delta. It was also found that the TPV treated with phenolic resin exhibited superior mechanical properties and the smallest vulcanized rubber domains. The TPV treated with the conventional peroxide co-agent curing system showed superior strength properties but had poor elastomeric properties. POLYM. ENG. SCI., 49:281-292, 2009. (C) 2008 Society of Plastics Engineers