Abstract: It was studied some peculiarities of trematods cercaria’ fauna producing by gastropoda mollusks - Lymnaeidae Rafinesque, 1815, Plаnorbidae Rafinesque, 1815, Physidae Fitziger, 1833 and Melanoididae Müller, 1774. In ponds of Syrdarya, Amudarya river (within Uzbekistan) and Zarafshan, natural infestation by trematods cercaria has been marked in 15 species of mollusks, Lymnaea (8 species), Planorbis (1 species), Gyraulus (2 species), Anisus (2 species), Physa (1 species), Costatella (1 species) and Melanoides (1 species). Total 27 species of cercaria were found belongs to trematods of 11 families - Fasсiolidae, Echinostomidae, Philophthalmidae, Paramphistomidae, Gastrothylacidae, Notocotylidae, Plagiorchidae, Sanguinicolidae, Strigeidae, Diplostomidae, Schistosomatidae and Bilharziellidae.