The article summarizes state of the art of the influence of external layer of Fe-Zn intermetallics on corrosion behaviour of galvanized steel in a fresh, hardened and chloride contaminated concrete. Current point of view on formation, composition and crystallography of particular intermetallic Fe-Zn phases, that are present in hot dip galvanized coating. External factors as alloying elements are involved as well. A corrosion resistance of these intermetallic layers (especially ζ-FeZn13) during exposure in concrete is evaluated finally.