Blends of Natural Rubber/Styrene Butadiene Rubber (NR/SBR) loaded with different ratios of N220 carbon black filler were prepared. The mechanical properties of pure blends and those loaded with different ratios of carbon black were investigated. The (50NR/50SBR), 40N220/(50NR/50SBR) blends were found to exhibit the highest values of tensile strength and elongation at break. The theoretical Mooney-Rivlin model was applied to NR/SBR and supports the result of stress-strain characteristics. The values of shore hardness (A) for all samples were measured and showed a marked increase by increasing the black content.