The temperate and subtropical grassland ecosystems are among the most threatened ecosystems in the world due to habitat loss. This study aimed to make a list of butterfly species present in native grassland fields in the city of Santa Maria, southern Brazil. The sampling field effort was 225 h using entomological nets, from 2009 to 2011. In total, 117 species of butterflies were recorded, distributed in six families and 18 subfamilies. Nymphalidae was the richest family, with 56 species, while Lycaenidae was the least rich family, with six species. Twenty species constitute new records for Santa Maria; while six of those are new records for the Central Depression Region of Rio Grande do Sul. In the face of global and local threats, it is urgent to increase efforts to study the biology and ecology of the grassland communities in order to provide support to biological conservation.