The　corrosion　behavior　of　hot　rolled　and　annealed(at　350°C　for　1　h)Al-Mg　alloys　5083　and　5A06　micro-alloyed　with　small　amount　of　Er　was　investigated　by　means　of　immersion　tests　and　electrochemical　dynamic　potential　cycle　polarization　measurements.　For　the　untreated　samples　and　those　after　immersion　tests,　the　morphology　and　microstructure　were　examined　by　optical　microscopy　(OM),　scan　electron　microscopy　(SEM),　transmission　electron　microscopy　(TEM)　together　with　energy　dispersion　spectrum　(EDS).　The　results　showed　that　both　5083　and　5A06　with　trace　Er　addition　were　of　good　corrosion　resistance,　and　the　corresponding　corrosion　rates　were　in　the　range　of　μA/cm2　when　measured　in　3.　5%　NaCl　solution.　The　trace　Er　addition　didn＇t　worsen　the　corrosion-resistance.　The　high　content　of　some　major　alloying　element　Mg　affected　greatly　the　corrosion　behavior,　and　the　heat　treatment　parameters　had　some　effect　as　well.