The representatives of the genus Sarcocystis are cyst forming coccidian protozoa parasites broadly prevalent in mammals, birds and reptiles. Sarcocystis parasites are characterized by an obligatory prey-predator two-host life cycle. Currently, over 220 Sarcocystis species are known. Some of Sarcocystis species are pathogenic organisms dangerous to humans, domestic and wild animals. A harmful effect of Sarcocystis mainly occurs in intermediate hosts and depends on the species of parasite, infection intensity and localization in the body. In Lithuania, Sarcocystis species forming sarcocysts in rodents, even-toed ungulates and birds were mainly studied. The ecology and diversity of Sarcocystis parasites were investigated using traditional morphological, DNA analysis methods and transmission experiments. Lithuanian scientists have described and named five Sarcocystis species, i. e. S. rodentifelis, S. wobeseri, S. cornixi, S. anasi, S. albifronsi; for the first time proved Sarcocystis rileyi infection in Europe; established definitive hosts of some Sarcocystis species.