Porous sedimentary rocks have been popular structural and artistic materials in many European countries for many centuries. These rocks are characterized by more or less porous structure and their mechanical properties are in close relationship with the pore system. The durability of porous rocks is to considerable extent controlled by these properties. The paper deals with pore system characteristics of selected porous sedimentary rocks found in Czech Republic. The dependences of compressive and bending strength on porosity of Czech sandstones were found in form of simple exponential functions.