The rodent families Echimyidae and Cricetidae are among the most diverse groups of mammals in Neotropical forests. There are 267 species of rodents in Brazil, of which 72 are endemic to the Brazilian Amazon. These rodents play a crucial role in forest dynamics as sensitive indicators of habitat and landscape change, as well as displaying a wide range of karyotypic diversity, including diploid numbers (2n) from 10 to 118 and autosomal fundamental numbers (FNa) from 14 to 168. The current study focused on the chromosomal diversity of rodents from the Echimyidae and Cricetidae families from the Hydro mining area in Paragominas, Pará, Brazil. Cytogenetic analysis was conducted using conventional staining, C-banding, and Fluorescence In Situ Hybridization (FISH) with telomeric probes on the species collected. We obtained the karyotypes of seven species: Calomys tener (2n=66/FNa=66), Hylaeamys megacephalus (2n=54/FNa=62), Necromys lasiurus (2n=34/FNa=34), Oligoryzomys sp. (2n=62/FNa=60), Pseudoryzomys simplex (2n=56/FNa=54) (Cricetidae), Makalata didelphoides (2n=66/FNa=84), and Proechimys roberti (2n=30/FNa=56) (Echimyidae). FISH using telomeric probes revealed only distal signals in all the seven species’ chromosomes. The karyotypes of all of the species are consistent with those previously described in the literature. We increased the distribution area of Calomys tener and Pseudoryzomys simplex to the Belém area of edemism, a species which can typically be found in the Cerrado region. This is evidence that the Amazon has become increasingly open due to deforestation and environmental degradation. The cytogenetic data from these species provide valuable insights for fauna mapping, conservation efforts, and evolutionary history.