This article discusses the five basic matrix structures in cast irons: ferrite, pearlite, bainite, martensite, and austenite. The alloying elements, used to enhance the corrosion resistance of cast irons, including silicon, nickel, chromium, copper, molybdenum, vanadium, and titanium, are reviewed. The article provides information on classes of the cast irons based on corrosion resistance. It describes the various forms of corrosion in cast irons, including graphitic corrosion, fretting corrosion, pitting and crevice corrosion, intergranular attack, erosion-corrosion, microbiologically induced corrosion, and stress-corrosion cracking. The cast irons suitable for the common corrosive environments are also discussed. The article reviews the coatings used on cast irons to enhance corrosion resistance, such as metallic, organic, conversion, and enamel coatings. It explains the basic parameters to be considered before selecting the cast irons for corrosion services.