The Wave Overtopping Simulator was developed in 2006 and destructive tests have been performed in February and March of 2007, 2008 and 2009 and will probably be continued in 2010. The tests show the behaviour of various inner slopes of dikes, embankments or levees under simulation of wave overtopping, up to a mean overtopping discharge of 125 l/s per m. In 2010 a Technical Report on strength of inner slopes of dikes against wave overtopping will be written, leading to new guidelines for the required five-yearly safety assessment of flood defence assets in the Netherlands. This paper will give a mid-term review and first guidance, based on 3 years of destructive testing. Till summer 2009 15 sections of dikes at 5 different locations in the Netherlands have been tested. The paper will give guidance to practical engineers, based on observations and analysis from all the testing so far. It also discusses the possible modifications in safety assessment.