Harrison and Walker described two "bradycnemids" from Romania in 1975: B. draculae and Heptasteornis andrewsi. These specimens had initially been assigned to the supposed pelecaniform bird Elopteryx nopcsai. Bradycneme means "ponderous leg", from Ancient Greek bradys (βραδύς) "slow, ponderous" + kneme (κνήμη) "leg", as the holotype, BMNH A1588, a 37.8 millimetres wide distal tibiotarsus found by Maud Eleanora Seeley, would be very stout if the animal had been an owl, indicating a body height of two metres. The specific name draculae is derived from Romanian dracul, "the dragon" and refers to Dracula.
Starting with Pierce Brodkorb, the specimens were soon compared to small theropod dinosaurs. These three genera Bradycneme, Elopteryx and Heptasteornis have been synonymized, split, and reassessed numerous times since then in part because of the fragmentary nature of the remains; there exist three proximal femora and three distal tibiotarsi, which may belong to one, two or three species. Usually, at least one of them is considered to be a troodontid.
In the most recent assessments, Bradycneme and Heptasteornis were found to be the same and most likely basal members of the Tetanurae in one study, but Darren Naish did not follow the synonymy and found Heptasteornis to be an alvarezsaurid. In a 2011 classification, Tom Holtz assigned Bradycneme to the alvareszauridae, along with Heptasteornis.