The effects of biofilm settlement on corrosion resistance of stainless steels in polar seawaters are not well known. In warmer conditions (Mediterranean sea) biofilm increases both the risk of localised corrosion onset and the propagation rate of corrosion attack. Corrosion tests carried out in Antarctica demonstrated that biofilm growth at about 0°C induced electrochemical effects less important than those occurring in warmer conditions. On the contrary, corrosion tests performed in similar environmental conditions at Ny-Aalesund (Svalbard) showed more severe corrosion attack than in Antarctica. This research aims: - to define the influence of biofilm on stainless steel corrosion resistance in polar seawater in the range of temperature between -1 and +5 °C, - to define if change in salinity can influence corrosion process, - to identify stainless steel grades which can be acceptable in such conditions (polar seawater seems to be somewhat less corrosive, which gives the possibility to use cheaper stainless steels).