A probabilistic fatigue Assessment Diagram (fAD) is proposed as a tool to guarantee a prescribed number of applied fatigue cycles with a conventional low probability of failure. The fatigue failure assessment curve is given by a power law described by two parameters: the fatigue initiation resistance and the fatigue initiation exponent. From the targeted applied stress range, it is possible to find the probability of failure and its associated safety factor. An example of fatigue life duration of a pipe steel submitted to hydrogen embrittlement is given.