The anatomy of a new, enormous phorusrhacid (Aves: Cariamae) from the Middle Miocene Collón Curá Formation of northwestern Patagonia (Río Negro province, Argentina) is described. The new phorusrhacid is known by a single specimen that consists of a nearly complete skull associated with a tarsometatarsus and a pedal phalanx. The new fossil is the largest known phorusrhacid and its morphology resembles more that of taxa traditionally grouped within phorusrhacines. Its skull—by far the best preserved among large phorusrhacids—provides a great deal of previously unknown anatomical information and indicates that reconstructions of the skull of gigantic phorusrhacids based on their smaller relatives are unwarranted.