ABSTRACT: Conflicting hypotheses prevail on the overwintering strategies of the Antarctic krill Euphausia superba due to the difficult accessibility of Antarctic waters, especially in winter, and hence, to the lack of seasonal data. This study reports on theseasonal lipid dynamics of E. superba (25 to 56 mm) collected in the Weddell Sea in late winter/spring, summer, autumn and mid-winter. Total lipid data provide evidence of large seasonal accumulation of reserve lipids in austral summer with a meanlipid content of 28.2% of dry mass and particularly in autumn, when mean lipid levels peak with 39.2% of dry mass. After the overwintering period mean lipid contents decrease to a minimum of 10.5% of dry mass, indicating extensive utilisation of lipidreserves during winter. These data suggest that lipids contribute significantly to the overwintering success of this extremely versatile species. Lipid class analyses of spring and summer specimens (10 to 56 mm) from the Antarctic Peninsula and theWeddell Sea revealed that not only triacylglycerol, but also phosphatidylcholine may serve as important storage lipids of E. superba. In the other dominant Antarctic krill species, E. crystallorophias (10 to 40 mm) and Thysanoessamacrura (10 to 27 mm), wax esters are the primary depot lipid, but phosphatidylcholine also functions as a storage lipid in these species. Phosphatidylcholine is unusual as a reserve lipid, being an essential component of biomembranes. In contrast,phosphatidylethanolamine, the other major phospholipid class, seems to have exclusively membrane functions, since it does not increase (in percent of dry mass) with increasing lipid levels in these 3 euphausiid species.