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.