Fatigue is the initiation and propagation of cracks in a material due to cyclic loading. Metal fatigue can cause premature failure of components and structures when subjected to low but cyclic loads. Worldwide, fatigue of metal components and structures results in annual losses that are estimated at billions of euros. Soete Laboratory develops experimental procedures (test methods + instrumentation) to evaluate fatigue damage accumulation and fatigue crack growth. The resulting data are used to calibrate and validate numerical models that are being developed to quantify fatigue damage and fatigue lifetime. More accurate prediction of fatigue will allow an optimized design of new structures, or will allow to assess the potential for lifetime extension of ageing infrastructure.