Axonopus P. Beauv. is an American genus with ca. 71 species, mainly distributed in northern South America, with some species apparently introduced to the Old World. A synoptical treatment of the Brazilian species is provided, including synonyms, ecological and geographic distribution, common names, comments on particular morphological features, and morphological relationships of the species. The morphological relationships with Digitaria, Paspalum, and Spheneria are discussed. Three names are synonymized: Axonopus apricus G. A. Black [= Axonopus marginatus (Trin.) Chase ex Hitchc.], Axonopus arcuatus (Mez) G. A. Black [= Axonopus polydactylus (Steud.) Dedecca], and Axonopus obtusifolius (Raddi) Chase var. rolfsii G. A. Black [= Axonopus furcatus (Flugge) Hitchc.]. Axonopus conduplicatus G. A. Black, Axonopus schultesii G. A. Black, and Axonopus eminens (Nees) G. A. Black are re-established. The name Paspalum chrysodactylon (Trin.) Doll var. glabratum Doll is lectotypified. Four species are excluded from the Brazilian flora. Thus, a total of 48 Axonopus species occur in Brazil, which 16 are endemic.