Principal morphological features of the cladocerans (Macrothricidae and Chydoridae), copepods (Diaptomidae) and branchiopods (Artemiidae) supplemented by short descriptions and photographs are presented. Bunops serricaudata (Daday, 1888), Anchistropus emarginatus Sars, 1862 Camptocercus fennicus Stenroos, 1898 Neutrodiaptomus (M.) pachypoditus (Rylov, 1925) Artemia sp. are reported for the first time in Irkutsk Region. All the species, except N. (M.) pachypoditus and Artemia sp. are rare and few in East Siberia. There is no significant difference in the external morphology of the species found and the European populations.