A very high proportion of recorded failures in service of engineering components and structures are the result of fatigue. ESDU 71009 summarises some general design principles that should be observed to minimise the risk of fatigue failure. The process of fatigue crack growth is described and the means of limiting it explained. The effect of local stresses is indicated together with several examples on improvement of fatigue strength by reduction of stress concentrations. The effect of component surface treatments is summarised and guidance is given on the selective fatigue strengths of various common engineering materials. ESDU 70016 and ESDU 75022 are complementary to this work.