This paper describes an experimental study carried out in a laboratory wave flume to quantify the influence of the relative water depth on the wave run-up over a smooth sloping structure. The runup measurements were carried out over practically important ranges of the wave steepness, the relative water depth and the structure slope. The results indicate an increase in the wave run-up at shallow depths compared to deep water conditions. This increase is up to about 20% for plunging breakers and is as much as 65% for surging breakers.