AbstractEquine protozoal myeloencephalitis (EPM) is a neurological disease caused bySarcocystis neurona. Immunofluorescence antibody tests (IFATs) have been widely used to identify exposure of horses toS. neuronain Brazil. Here we used IFAT to search for IgG antibodies againstSarcocystis falcatula-like (Dal-CG23) andS. neurona(SN138) in sera from 342 horses sampled in Campo Grande, Mato Grosso do Sul state (Midwestern), and São Paulo, São Paulo state (Southeastern), Brazil. The 1:25 cutoff value was chosen to maximize sensitivity of the test. IgG antibodies againstS. neuronawere detected in 239 horses (69.88%), whereas IgG antibodies againstS. falcatula-like were detected in 177 horses (51.75%). Sera from 132 horses (38.59%) reacted against both isolates. Absence of reactivity was evidenced in 58/342 horses (16.95%). The lower cutoff used, and the presence of opossums infected withS. falcatula-like andSarcocystisspp. in the regions where the horses were sampled, might justify the high seroprevalence observed here. Owing to the similarity among antigens targeted in immunoassays, reports onS. neurona-seropositive horses in Brazil may also derive from the exposure of horses to otherSarcocystisspecies. The role of otherSarcocystisspecies in causing neurological diseases in horses in Brazil remains unclear.