Among the Miocene sites excavated since 1991 by the Namibia Paleontology Expedition, two located in the Orange River Valley have yielded rhinoceros remains: Arrisdrift and Auchas Mine. An atlas vertebra and a mandibular fragment, both encrusted with sediment and thus specifically undeterminable, have been recorded from Auchas Mine. A fine lot of generally well preserved rhino material was found at Arrisdrift among a very diverse Vertebrate fauna. All but one of the 112 rhino pieces constitute a homogeneous sample pertaining to a very large species of cursorial rhino first described in 2000, Diceros australis Guérin, of which Arrisdrift is the type locality. The large form from Arrisdrift seems to be the largest of the African Miocene Rhinos; the size and proportions of the metapodials and the other limb bones suggest a strong analogy with Diceros gr. pachygnathus-neumayri of the Upper Miocene of the Near East; the type of construction of the upper cheek teeth, in particular the fourth premolar, is of Dicerotine kind and presents, as do the dimensions, close resemblances with Diceros douariensis of the Upper Miocene of North Africa and Italy; the mandible shows analogies with the Dicerotines, especially the apparently short symphysis. Diceros australis is thus by far the oldest known species of the subfamily; the small reduced lower tusks could represent an evolutionary stage prior to the loss of the entire anterior dentition, which is effective in the subfamily since the Upper Middle Miocene. The exception among the Arrisdrift rhino material is an isolated magnum which suggests a small to medium sized short-legged form, probably Chilotheridium pattersoni, a species described from Loperot in Kenya, the age of which is about the same as Arrisdrift, i.e. 17 Ma.