This monograph presents the results of many years of research on the role of earthworms, arthropods, mollusks, etc. as intermediate hosts of helminths in the mountain zones of Uzbekistan. At the same time, the systematic position of the identified larval forms of helminths is described and our observations on their intermediate hosts are presented. We present data on localization of larvae in host organisms, extensiveness (EI) and intensiveness (II) of infestation, location of detection, etc. For larval forms of helminths observed for the first time, as well as for larvae detected in new intermediate hosts, descriptions and original drawings are provided.