Natural rubber/ethylene-propylene-diene monomer (NR/EPDM) rubber blends of composition 75/25 with 0, 2, 4, 6, 8, and 10 phr (parts per hundred rubber) halloysite nanotubes (HNTs) were prepared by two-roll mill. The effect of HNTs on the cure characteristics and mechanical properties of the NR/EPDM nanocomposites were studied. The effect of HNTs loading on the morphological, physical, swelling resistance and compression set of nanocomposites based on NR/EPDM was also investigated. Tensile strength tests revealed that the HNTs-reinforced NR/EPDM composite could resist 84% greater strength to break than the NR/EPDM blend without reinforcement. The introduction of HNTs into the NR/EPDM rubber matrix induced a rough morphology in the fracture surface, and a well-dispersed structure was obtained with the inclusion of up to 8 phr of HNTs, according to the morphological analyses.