Isolated embryonic membranes (i.e. the outer cuticular membrane, the fibrous layer, the inner cuticular membrane and the hatching membrane) and homogenates of incubated, decapsulated cysts of 16 populations from five Artemia species (Crustacea, Anostraca) were examined by sodium dodecyl-sulphate polyacrylamide gel electrophoresis. Characteristic differences in major polypeptides between 45 and 205 kD were seen. These differences might be used as markers for identification of different Artemia species. The validity of this approach in characterizing Artemia populations is discussed.