This paper focuses on the methodology used to determine the design wave impact loading on a pedestrian walkway on top of a breakwater. The wave loading on the walkway is an impact loading with high forces acting for short times. The actual impact loading is depending on the characteristics of the overtopping waves ánd on the dynamic characteristics of the pedestrian walkway. In order to assess the impact effect of the overtopping waves on the structure tests are run on a physical 1/20 scale model is built and run in the large wave flume of Flanders Hydraulics Research Laboratory (Antwerp, Belgium). Each run generates a series of waves in the flume shoaling up the model breakwater with the model pedestrian walkway situated on top of it. The physical model cannot represent all the relevant walkway material properties like mass and elasticity, such that the forces in the (flexible) connections between walkway and breakwater could be derived accurately for the prototype design. Therefore the model is solely used to assess the integral wave impact loading on the walkway, whose boundary conditions in the model have been adapted for measuring time series of horizontal and vertical reaction forces with load cells. These time series are converted to actual wave loading on the model by using a numerical model for the dynamic response of the scale model, thus taking into account the dynamic characteristics of the scale model. Doing so, a numerical filter is derived to eliminate possible eigenmodes due to the characteristics of the model set up. Time series of the reaction forces were used as input for the numerical filter. Eventually the design values for the wave impact loading in prototype are derived using Froude scaling (1/8000 = 1/20^3).