High strength low alloy steels provide better mechanical properties than conventional carbon steels. Thus, they allow a weight reduction of the components, resulting in lower production and transport costs. In addition to static loading, many components have also to withstand fatigue due to dynamic loads. A main aspect during the welding process is the influence on microstructure and mechanical properties. To estimate this influence on base material and fatigue life, the base material was tested prior to welding. Consequently, the main focus of this thesis is the influence of welding parameters, especially the total heat input and the filler materials, on the fatigue behaviour of high strength low alloy steels. These investigations give important insights of the fatigue behaviour of welded high strength low alloy steels. Finally, the findings and their application in practice are discussed.