EN
To give the answer to this question the author examined muscles of 132 horses. The samples were taken from muscles of: diaphragm, maxilla, tongue, internal part of the pelvis, oesophagus, abdominal wall and the heart. The technic of examination did not differ from the routine examination technic accepted generally in examining pork flesh. Besides the author examined histologically samples of heat muscle and other striated muscle of 100 additional horses. In none of the examined samples Sarcocystis was present. In the paper are given data from the literatura concerning sarcosporidiosis and description of a microscopical picture ot one case of sarcosporidiosis in a horse which was operated on because of a tumor on its shoulder.