ISO 22889:2007 specifies methods for determining the resistance to stable crack extension in terms of crack opening displacement and critical crack tip opening angle for homogeneous metallic materials by the quasistatic loading of cracked specimens that exhibit low constraint to plastic deformation. Compact and middle-cracked tension specimens are notched, precracked by fatigue, and tested under slowly increasing displacement.ISO 22889:2007 describes methods covering tests on specimens not satisfying requirements for size-insensitive fracture properties; namely, compact specimens and middle-cracked tension specimens in relatively thin gauges.Methods are given for determining the crack extension resistance curve. Methods for determining point values of fracture toughness for the middle-cracked tension specimen are also given.