The effect of addition of chloroprene rubber (CR) on the dispersion of silica in EPDM (ethylene-propylene-diene terpolymer) was studied. It was observed that physical properties of the vulcanizates could be significantly increased at the EPDM : CR blend ratio of 92.5 : 7.5. SEM micrographs also indicated that incorporation of CR into EPDM improves the network structure of the resulting vulcanizates. (C) 2004 Wiley Periodicals, Inc.