The influence of microorganism-induced surface modifications on the corrosion behaviour of 5083 H11 aluminium alloy was studied. Pre-immersion in natural seawater (between 15 days and 2 months) led to the growth of a dense oxy-hydroxyde layer on the AA5083 surface. This layer led to a decrease in the cathodic and corrosion current densities, and an increase in the passivity domain on the polarisation curves plotted in chloride-containing sulphate solution for pre-immersed samples compared to bare samples. This improvement in the corrosion behaviour of AA5083 depended on the alloy microstructure, and the sunlight exposure during the pre-immersion in natural seawater.