With the purpose of verify the presence of larvae from the genus Gasterophilus in the Rio Grande do Sul State, a study was undertaken using 395 horses taken to slaughter in the city of Pelotas. The material analysis revealed that 126 animals (31,90%) presented infection, with 100 animals (25, infected by Gasterophilus nasalis, and 47 animals (11,90%) infected by G intestinalis. These results also represent the first report of the definite establishment of G intestinalis as a horse parasite in Brazil. The probable implications of G. intestinalis occurrence in Brazil are discussed.