Three new species of Hyphessobrycon (Characiformes: Characidae) are described from the upper rio Araguaia basin. Hyphessobrycon langeanii n. sp. is distinguished from all congeners by the presence of a well-defined, round humeral spot, a reticulate color pattern, a broad, horizontally-elongate caudal-peduncle blotch, and a relatively wide, faint midlateral dark stripe. Hyphessobrycon eilyos n. sp. is distinguished from all congeners by the absence of humeral and caudal spots; by the presence of numerous dark chromatophores on the lateral surface of the body, intensely concentrated on the ventral region from the pelvic-fin origin to the end of the caudal-fin base, dorsal, adipose, and caudal fins with carmine red pigmentation in life; and the presence of 7-11 maxillary teeth. Hyphessobrycon weitzmanorum n. sp. is distinguished from all congeners by the combination of the possession of two humeral spots and a general dark color pattern. These three new species, along with Creagrutus molinus (Characidae), Apareiodon tigrinus (Parodontidae), Aspidoras velites (Callichthyidae), an undescribed member of the Hypoptopomatinae (Loricariidae), Cnesterodon septentrionalis (Poeciliidae), and Simpsonichthys cholopteryx (Rivulidae), all of which are apparently endemic of the upper rio Araguaia, indicate that this area is a previously unrecognized area of endemism.