An ultra-thin MgO film of two monolayers (ML) was successfully grown onto Ag(111) by repeating twice RT adsorption of Mg atomic monolayer, RT oxidation and 725 K thermal annealing under UHV conditions. Using Auger electron spectroscopy, low electron energy diffraction and scanning tunneling microscopy/spectroscopy, we report here formation of MgO(1x1) and MgO(1x1)-R30 epitaxial layers, consistent with the growth of a MgO(111) polar film onto the silver surface and composed of patches having extended slight corrugation oriented along defined directions with respect to the substrate.