African bullfrogs (Pyxicephalus) are large, impressive anurans which display reversed sexual dimorphism, male-male combat and male parental care. Three species are currently recognized from throughout the arid savannas of Africa. Morphometric data have traditionally underpinned the diagnoses of species within Pyxicephalus. However, the two most commonly encountered species (P. adspersus and P. edulis) are problematic to diagnose: none of the four traditionally used characters separate all individuals from all regions. This study aimed to examine the morphology of all previously named taxa (valid or synonymized), assess the extent of geographical variation across Africa, and identify consistent diagnostic characters for each species.