Myositis eosinophilica (ME) in cattle is characterised by grey-greenish lesions in the muscular tissue, which is a reason for condemnation. There are histological and immunological indications that Sarcocystis is involved in the pathogenesis of myosistis eosinophilica. Using a digestion-technique, a quantitative analysis of Sarcocystis was performed on heart tissue of normal carcasses (n=24) and of carcasses condemned for ME (n=10) in Belgium. The incidence of Sarcocystis was 100% in both groups. In the carcasses with myosistis eosinophilica, less cystozoits per gram heart tissue were counted than in normal carcasses. A possible explanation for this is the hypothesis which suggests that myositis eosinophilica in cattle is the result of sarcocyst destruction by a hypersensitivity-reaction. This hypersensitivity-reaction may be the cause of the grey-greenish lesions observed in ME.