ESDU 02016 provides both static and dynamic fracture toughness data for over 150 specifications of cast iron in the grey, chilled, white, malleable, ductile and compacted graphite forms. Also included are detailed descriptions of the general nature of these irons, and their respective fracture characteristics. Additionally, the factors likely to influence a measured fracture toughness value for a given material are considered, as are the peculiarities experienced with fracture toughness testing of cast iron. The fracture toughness data appearing in the Item fall within the temperature ranges of interest for practical applications, with the full brittle-to-ductile transition spectrum being considered for a number of ductile irons. The applicability of the Barsom Temperature Shift to static fracture toughness values for ductile iron is also investigated. The Item contains an in-depth statistical analysis, offering the user two methods for obtaining a design allowable fracture toughness value with a prescribed level of confidence. The first method is the result of studies of the correlation between the fracture toughness of various forms of cast iron and other parameters: hardness (white and grey cast irons), tensile strength (grey cast iron), and temperature (ductile iron). The second method is based on the provision of mean fracture toughness values for each type of material, from which design allowable values can be calculated. A worked example illustrates the implementation of these techniques, and guidance is given on the applicability of each method. Standard requirements for cast iron compositions and mechanical properties are provided, and discrepancies in cast iron fracture toughness measurements obtained through the use of different variants of a standard test procedure are considered.