This paper focus on experiments on run-up of strongly nonlinear waves on a moderately steep beach of 10.5deg inclination. Velocity fields are obtained by the PIV (Particle Image Velocimetry) technique. Acceleration measurements are also attempted, but it is difficult to obtain useful results in every case. In addition free surface profiles are extracted from digital images and wave resistance probes. Several non-breaking incident waves are measured and compared with theory in deep water as well as under run-up. However, the main theme is run-up of steep waves at the brink of breaking, that is assumed to be a good starting point approaching a detailed study of bore run-up. In some cases these are found to be temporarily slightly overturning in the first stages of run-up, without developing neither a plunger nor appreciable spilling. This feature is discussed in view of acceleration measurements and with reference to the dam-break problem. Effects of scaling, as well as three dimensional features observed for the steepest waves, are also briefly discussed.