Impulse waves in reservoirs, lakes, oceans and bays inflict a potential hazard on the human civilization along waterways, coastal areas and Alpine regions. Experimental research was conducted at the Swiss Laboratory of Hydraulics (VAW) to assess the risk from landslide-generated impulse waves. Analogously, the Centro Elettrotecnico Sperimentale Italiano (CESI) performed numerical simulations of initial landslide and consequent impulse wave propagation using two mathematical models. Experimental and simulated test results were compared for an individual test series in a flume with various stillwater depths, landslide volumes and impact velocities of laboratory scale. Water wave profiles were compared regarding the basic assumptions of the coupled mathematical models. The resultant wave heights were acceptably forecast by the conservative shallow-water equations, although the first wave peaks exhibited comparatively large flank steepness. Excluding spurious random effects, the relative differences between measured and numerically computed maximum wave heights ranged within ±20%, which can be considered satisfactory from the engineering point of view. Keywords: dispersion, flank steepness, granular landslide, numerical simulation, wave probe, propagation, rigid block, wave peak 1 Dr., VAW, ETH-Zentrum, CH-8092 Zürich, Switzerland 2 Dr., CESI SpA, Via R. Rubattino 54, I-20134 Milano, Italy 3 Eng., CESI SpA, Via R. Rubattino 54, I-20134 Milano, Italy