Samples of heart, tongue, oesophagus and diaphragm muscle from twenty-two naturally infected roe deer (Capreolus capreolus) harvested in central Italy were examined for sarcosporidiasis. The structure of Sarcocystis spp. muscle cysts was examined by light and electron microscopy. Only one type of thin-walled cyst was distinguished by light microscopy. Electron microscopy showed cysts having a thin highly folded primary cyst wall, without fibrillar material, that formed thin hair-like protrusions often having a T-form, especially close to host cell mithocondria. The cysts appeared to belong to a single Sarcocystis sp. so that all the animals had monospecific infections. This cyst was compared with cysts described in other cervid in an attempt to determine if single or multiple species of the genus Sarcocystis occur in the Cervidae. Apparently, a single Sarcocystis sp. with a low specificity for the intermediate host can infect the Cervidae.