We have studied the effect of transpolyoctylene rubber(TOR) on the mechanical and thermal properties of thermoplastic elastomers from dynamically vulcanized natural rubber(NR)-isotactic polypropylene(iPP) blends. The addition of suitable amount of TOR into the rubber phase leads to the increase in tensile strength, modulus as well as ultimate strain. From dynamic mechanical analysis, it was found that the addition of TOR into the blends does not lead to any increase in compatibility of the NR and iPP. The increase in tensile properties is thought to be arised by the increase in elasticiy of the rubber phase and the decrease in sizes of rubber domain.