Rubbery ionomer based on zinc salt of sulfonated natural rubber (Zn-SNR) was employed as a new compatibilizer to prepare blends of natural rubber (NR) and chlorosulfonatedpolyethylene (CSM) with different compositions by melt mixing process. Epoxidized natural rubber (ENR), known as an effective compatibilizer for such blends, was also incorporated into the blends. The role of ionomer and ENR on NR/CSM blend properties and morphology was evaluated by mean of tensile measurement, oil resistance testing, DMTA and SEM. The tensile properties and oil resistance of the blends were found to increase with respect to CSM content, and increased further on compatibilization with Zn-SNR and ENR. The blends compatibilized with Zn-SNR showed a similar or higher level of improvement in tensile strength and elongation at break as compared to those of ENR. The tensile strength for all of the compatibilized blends was greater than that of corresponding neat blends by 23 to 113 %. The mechanism for enhancing in tensile properties of the blends using the Zn-SNR compatibilizing agent has been proposed. The observation of DMTA and SEM showed that the blends were two-separated phase morphology. However, the addition of Zn-SNR to NR/CSM blends resulted in promoted compatibility as indicated by a shift in the tan 6 peak of CSM to lower temperature, a reduction in dispersed phase size and better adhesion between NR and CSM. These results demonstrated that the Zn-SNR is a new reactive compatibilizer for NR and CSM blends.