Alloy cast irons are casting alloys based on the Fe-C-Si system that contain one or more alloying elements added to enhance one or more useful properties. This article discusses the composition of different types of alloy cast iron, including white cast irons, corrosion-resistant cast irons, heat-resistant cast irons, and abrasion-resistant cast irons. It provides information on the effect of the alloying element on their high-temperature properties. The article also discusses the microstructure and mechanical properties of alloy cast irons.