This paper is dedicated to long-term atmospheric corrosion behaviour of magnesium alloys. Five different magnesium alloys, namely, AZ31, AM60, AZ61, AZ80, and AZ91, were exposed for 4 years under harsh conditions at the marine corrosion site of Brest (France). From the results, the corrosion performance increased in the following order: AZ31 < AM60 < AZ91 < AZ61 < AZ80. The corrosion was highly localised during the first year of exposure, but more general corrosion prevailed after long-term exposure. All materials followed a power law with rather similar kinetics of corrosion. The observed difference in the corrosion performance of the alloys was explained by the amount of secondary phases as well as that of the Al-content in the α-Mg phase