Resumo. ABSTRACT Litter ant species found in four sites located in northwestern Rio Grande do Sul state were listed in this study to verify the impact of human activities conducted in rural areas. The method used for the collection of litter ants was the Winkler extractor. There were collected 6,300 specimens belonging to eight subfamilies, 18 tribes, 31 genera and 108 species. Native forest presented the highest richness observed with 90 species collected, followed by 65 eucalyptus species, and agriculture and pasture with 20 exotic species each. Margalef’s diversity index was 11.21 for area with native forest, 8.37 for eucalypt, 3.48 for agriculture, and 2.71 in exotic pasture area. The Shannon’s diversity indices obtained were 2.89, 3.15, 2.43 and 1.98 and equitability indices of 0.64, 0.75, 0.84 and 0.66 for areas with native forest, eucalyptus, agriculture and exotic pasture, respectively. The highest diversity index for the eucalypt area may be due to the age of the forest (28 years) and the fact that it has not been managed as well as due to the presence of understory of native species, forming a continuous canopy and thick litter layer. On the other hand, since the native forest has suffered human interventions, it has a lower Shannon’s diversity index compared to the eucalypt area.