Lipid composition has proved particularly useful in the taxonomy of mi
croorganisms. The most spectacular grouping that can be made among pro
karyotes, on the basis of lipid analysis, is the Archaea whose membran
es are based on isopranoid glycerol ether lipids. This presentation is
meant to give an updated general survey of the structural features of
lipids of Archaea and the significance of lipid composition in archae
al taxonomy.