This study has investigated the effect of different amounts of Cr and Zr additions on the microstructure and mechanical properties of A356 alloy modified with strontium. The microstructure and phase examination were performed using an optical microscope, scanning electron microscope and XRD analysis, whereas mechanical properties were investigated via tensile testing and hardness measurements. Two-dimensional Weibull distribution was used to determine the effect of Cr and Zr additions on mechanical properties of A356 alloy. It was found that the most significant effect of Cr and Zr added was over the morphology of Al-Si-Fe intermetallics. The addition of Cr and Zr led to the formation of Cr/Zr-based intermetallics in precipitates and fish-bone-like morphologies. It was observed that increasing the amount of Cr and Zr had resulted in an increase in ductility of A356.