This paper presents a probabilistic assessment model for linear elastic fracture mechanics (LEFM). The model allows the determination of the failure probability of a structure subjected to fatigue loading. The distributions of the random variables for civil engineering structures are provided, and the relative importance of these random variables is determined. An example of a bridge detail is provided in order to show the application of the model. Partial factors are derived for the case of fatigue of welded joints in civil engineering structures. The failure probability appears to be relatively insensitive to the failure criterion (attainment of a through-thickness crack or fracture) when considering the total fatigue life.