This International Standard defines the general procedures for fatigue testing of fibre-reinforced plastic composites under cyclic loading conditions of constant amplitude and constant frequency. Although these general procedures are applicable to all modes of testing and test machine control, care will be required in their application in each case. Prior experience has been mainly with tensile and flexural fatigue testing based on the equivalent static (monotonic) test methods. Fatigue tests on unidirectionally reinforced carbon-fibre systems in the fibre direction are particularly difficult to perform. In some cases, such as fracture toughness crack propagation, specific tests may exist that should be used in preference to this International Standard.