Technical Abstract: Coccidia are obligatory intracellular protozoan parasites. Eimeria, Isospora, Cryptosporidium, Toxoplasma, and Sarcocystis are important genera of protozoal parasites of mammals and birds. Domestic animals may be infected with several species of coccidia but usually only a few species are pathogenic for a given host. In the present paper we review coccidiosis in pigs caused by these organisms.