Technical Abstract: Sarcocystis neurona is the primary causative agent of equine protozoal myeleoencephalitis (EPM), a common neurologic disease of horses in Americas. We have developed a set of enzyme-linked immunosorbent assays (ELISAs) based on the four major surface antigens of S. neurona (SnSAGs) to analyze the equine antibody response to S. neurona. The SnSAG ELISAs were validated with a sample set of 37 equine sera that had been characterized by western blot against total S. nmeurona parasite antigen, the current gold standard for S. neorona serology. The rSnSAG2 ELISA showed the highest sensitivity at 95.5%. In contrast, only 45.5% sensitivity was achieved with the rSaSAG1 ELISA, indicating that this antigen may not be a reliable serological marker for detecting S. neurona infection in horses. Importantly, the ELISAs did not show cross-reactivity with antisera to Sarcocystis fayeri or Neospora hughesi, two other equine coccidian parasites. The SnSAG ELISAs will be valuable tools for elucidating the equine immune response against S. neurona infection, which may help in understanding the pathobiology of this accidental parasite/host interaction. Additionally, the ELISAs have potential for use as immunodiagnostic tests to aid in the identification of horses affected by EPM.