Since Price (1929) published his synopsis of the family Schistosomatidae, numerous species of adult worms have been described and new genera and subfamilies have been proposed. In some instances relationships of species and genera seem uncertain and the bases of some genera appear questionable. A number of life cycles have been elucidated, but there still remain many species of adult worms with unsolved life cycle, and cercariae have been described without knowledge of adult stages. It was thought that cytological studies might help insolving some of the taxonomic problems in this group and eventually might furnish clues as to the origin of the dioecious schistosomes from hermaphroditic ancestors. The present paper deals with chromosomes in cercarial embryos of 9 species of schistosomes in 6 genera.