Technical Abstract: Protozoan parasites of the genus Sarcocystis are prevalent in the muscles of cattle and sheep. Some species can be seen with the naked eye whereas others are microscopic. All species require two hosts in a prey-predator relationship to complete their life cycle. Asexual stages develop only in intermediate hosts when, after ingesting sporocysts in food or water contaminated with animal feces, they become infected with stages that develop in blood vessels and muscles. Sexual stages develop only in definitive hosts when, after eating sarcocysts in animal muscles (meat), they become infected with stages that develop in the gastrointestinal tract. Humans can serve in as both intermediate and definitive hosts for different species of Sarcocystis. Detection methods, means of identification, prevalence of infection, transmission routes, clinical signs, diagnostics, and methods of treatment and prevention are described in this chapter.