Coatings are very important for numerous industrial applications such as increasing the wear resistance of tools, providing thermal conductivity to components in engines or electric conductivity in microelectric devices. The mechanical properties of the coatings are of prime concern. The practicability of performing miniaturized compression tests in order to determine mechanical properties of various thin films was analysed. A polycrystalline tungsten coating and as comparison a tungsten single crystal were tested. Furthermore two single crystal hard coatings (vanadium nitride and titanium nitride) were compression tested. The compression samples were fabricated using a focused ion beam microscope. The deformation of the sample was observed and in-situ recorded by a scanning electron microscope. From the measured load-displacement data true stress-true strain curves were calculated and discussed.