In this work, blends of fluoroelastomer (FKM), natural rubber (NR) along with high-density polyethylene (HDPE) by dynamic vulcanization using peroxide (DBPH, DCP) as a curing agent were prepared. HDPE was melt-mixed with NR and FKM at different compositions (HDPE/FKM/NR i. e. 30/60/10, 30/55/15, 30/50/20, and 30/35/35% wt) using an internal mixer at 1508C and 50 rpm rotor speed. The mechanical properties and oil swelling resistances of these blends were analyzed according to ISO 37 (Type 1) and ASTM D471, respectively. The results suggest that DBPH works better as a curing agent for the dynamic vulcanization system than DCP. The optimum mechanical properties and oil resistance were revealed in 30/50/20 and 30/60/10 HDPE/ FKM/NR, being dynamic vulcanized with DBPH, respectively. In addition, was found that a dispersed HDPE phase shows the percent crystallinity in the range of 53% to 55% upon increasing the NR content. The SEM micrographs reveal the NR phase is well dispersed in FKM as small particles. POLYM. ENG. SCI., 51: 1484-1488, 2011. (C) 2011 Society of Plastics Engineers