This thesis presents experiments on run-up of solitary waves on a beach of 10◦ inclination. The purpose of this study is to find out what causes the lower maximum run-up heights in experimental results compared with results from numerical models that are based on dispersive long wave theory and full potential theory. The experimental work includes the surface elevation, the velocity field close to the beach and tracing of the moving shoreline. It is found that the main deviation from theory appears in the later stage of the inundation. And the conclusion made is that the discrepancies between theory and experiment are most likely due to viscous effects in the boundary layer.