ESDU 96013 provides over 4000 values of plane strain fracture toughness for 23 US standard material specification aluminium alloys. The data are presented in tabular form, providing details of test temperature, crack orientation with respect to grain flow, proof stress, chemical composition and heat treatment. All data relate to non-corrosive environments at temperatures from - 253 to 149 degrees C (- 423 to 300 degrees F). Typical dependence of fracture toughness and proof stress on temperature is illustrated graphically. After a brief explanation of the importance of plane strain fracture toughness in design, test conditions, presentation of data and factors that affect fracture toughness are discussed. The method is explained by which statistical analysis is applied to the data to obtain with a chosen confidence design allowable values of fracture toughness, both from samples exceeding 30 values and from smaller samples of between 8 and 30 values. A worked example illustrates the use of results from that analysis with the data.