Individual sporocysts containing 4 sporozoites were shed in the feces of dogs, foxes, and raccoons after ingestion of bovine tissue infected with Sarcocystis fusiformis bradyzoites. No sporocysts were shed by cats, monkeys, swine, skunks, ferrets, rats, guinea pigs, or rabbits after ingestion of similar bovine tissue. The shedding of sporocysts by dogs that had ingested tissue from a bovine experimentally infected with sporocysts from coyotes indicated that both canids were definitive hosts for the same species of Sarcocystis. After oral inoculation wtih sporocysts from dogs previously fed infected bovine heart, a calf became infected; but sheep, swine, rats, mice, rabbits, and monkeys did not. These results show the narrow specificity of the asexual stages of this parasite for the bovine intermediate host and the wider, though still restricted, host range of the sexual stages of this parasite for coyotes, dogs, foxes, and raccoons, the definitive hosts.