Geomembranes in composite liners of landfills may not be damaged by coarse grains of the drainage lay- ‘ er. In Germany different types of protection layers are used: mineral layers, geosynthetic layers or combinations of both. Suitable protection layers, especially clayfilled and sandfilled mats, are in development. A stanclardiz.ed procedure for testing the mechanical effectiveness of protection layers is required. Selected results of research programmes to investigate the effect of <µfferent parameters on the protection effectiveness and to develop a stanclardiz.ed testing procedure and evaluation method are described. Preliminary conclusions are drawn.