Polypropylene copolymer(PPC) and high impact polystyrene(HIPS) are incompatible and have been well recognized. In this study, styrene-butadiene copolymer(SBC) compatibilizer in the blends PPC/HIPS. Compatibility of blends of PPC with HIPS was studied by mechanical properties. Tensile strength, flexural strength, izod impact strength and elongation at break is also drastically decreased by adding small amount of PPC.