At Vienna University of Technology, Institute of Structural Engineering, Research Centre of Steel Structures, a new, extremely slender steel-concrete-steel composite (SCSC) plate is under investigation to meet the requirements of todays standards related to the geometric conditions and noise emission in the substitution of old railway bridges. The multi-layer structure of the plate consists of two steel cover plates with an unreinforced concrete core, hence the name of sandwich plate. Perforated shear connectors, welded alternately to only one of the outer steel plates, work together to ensure the transmission of the shear flow between the outer plates, by the activation of diagonal, horizontal concrete compression struts between neighboring dowel bars. In addition to the distribution of the vertical loads in cross direction to the main girders, the SCSC deck slab also acts as main girder bottom flanges. Investigations on the static loadbearing capacity as well as an explanation of the load-carrying mechanism of the SCSC plate were made in [1, 2, 3]. The next step towards the application of the SCSC plate as a deck slab for railway bridges was to investigate the fatigue behaviour of this structural element. Evaluation of the fatigue behaviour of the SCSC plate is presented in this work, focusing on the fatigue life of shear connectors. In the course of research nonlinear, three-dimensional finite element models served as basis for the lifetime calculations using the local strain-life method. The aim was to investigate the relation between the range of traffic load (Load Model 71 ) and the bearable number of load cycles of the SCSC plate till crack initiation in the shear connectors. For this purpose, extensive parameter studies were carried out, which examined the influence of many modeling parameters on the lifetime, as well as real influences such as steel grade, concrete grade and ballast beg height, which can be varied during the planning and realization of a bridge project. Finally, the Wöhler curves were defined analogously to the fatigue strength categories specified in Eurocode 3 : After linearization of their nonlinear functions using the least squares method they were defined by the slope and the sustainable traffic load range at two million cycles.