Zoonoses include many parasites; one of them is Sarcocystis, infecting man through infected animal muscles. Animals may act as a reservoir host, while being harmful to man. M&M: Samples were collected from 100 cows and 100 buffaloes from Sohag slaughter houses. It included samples from the tongue, heart, oesophageal and skeletal muscles. Macroscopic examinations were followed by microscopic ones on the impression smears, compression of muscles.

   Histological sections and transmission electron microscope (TEM) studies were done on positive cases. The results included: Sarcocystis infection rate of cows was 84%. By the use of both light microscope and TEM, examination of the cyst wall thickness and other morphological characters. Two species of Sarcocystis were detected: 1- Sarcocystis cruzi with a membrane provided with hair-like villar protrusions folded over the surface of the cyst. These protrusions were rod-like, round, oval or irregular in shape and were approximately parallel to the cyst surface. 2- Sarcocystis hominis characterized by a cyst wall consisting of cylindrical finger-like villar protrusions .The protrusions were perpendicular on the cyst surface with broad tips and contain microfilaments. Buffaloes' muscle samples revealed an infection rate of 28%. The macroscpic fusiform-shaped species only was detected (Sarcocystis fusiformis). By TEM, the cyst wall had microfilaments.