The mosquito community from remote locations toward the southern border of the Brazilian State of Amazonas, in four localities along the Liberdade and Gregório Rivers, was sampled using CDC and Malaise traps, complemented with net sweeping and immature collections. During May 2011, 190 collections yielded 13,012 mosquitoes, from 15 genera and 112 different species, together with 10 morphospecies, which may represent new undescribed taxa. Among the species collected, there are two new geographical distribution records for the State of Amazonas. Culex, the most abundant genus, also had the highest number of species. Both Aedes and Uranotaenia had the second highest number of species, although they were the second and seventh most abundant, respectively. The most abundant species were Aedes (Ochlerotatus) fulvus (Wiedemann), Aedes (Ochlerotatus) nubilus (Theobald), Culex (Culex) mollis Dyar & Knab, Nyssorhynchus (Nyssorhynchus) oswaldoi sensu lato, Culex (Melanoconion) pedroi Sirivanakarn & Belkin, and Culex (Melanoconion) gnomatos Sallum, Hutchings & Ferreira. The epidemiological implications of mosquito species are discussed and compared with other mosquito inventories from the Amazon region. These results represent the first standardized mosquito inventories of the Liberdade and Gregório Rivers, with the identification of 112 species and 10 morphospecies, within the municipalities of Ipixuna and Eirunepé, from which we have only few records in the published literature.