The Tibetan antelope is the sole species in the genus Pantholops, named after the Greek for "all antelope". It was formerly classified in the then-subfamily Antilopinae (now thought to be the tribe Antilopini), but morphological and molecular evidence led to it being placed in its own subfamily, Pantholopinae, closely allied to goat-antelopes of the then-subfamily Caprinae. However, this has been disputed, and most authorities now consider the Tibetan antelope to be a true member of the Caprinae, or the tribe Caprini. Phylogenetic evidence indicates that Pantholops is the most basal member of the Caprinae / Caprini, and belongs to its own tribe or subtribe, Pantholopini or Pantholopina.
Although the genus Pantholops is currently monotypic, a fossil species, P. hundesiensis, is known from the Pleistocene of Tibet. It was slightly smaller than the living species, with a narrower skull. In addition, the fossil genus Qurliqnoria, from the Miocene of China, is thought to be an early member of the Pantholopini, which diverged from the goat-antelopes around this time.
The Tibetan antelope is a medium-sized antelope, with a shoulder height of about 83 cm (32+1⁄2 in) in males, and 74 cm (29 in) in females. Males are significantly larger than females, weighing about 39 kg (86 lb), compared with 26 kg (57 lb), and can also be readily distinguished by the presence of horns and by black stripes on the legs, both of which the females lack. The coat is pale fawn to reddish-brown, with a whitish belly, and is particularly thick and woolly. The face is almost black in colour, with prominent nasal swellings that have a paler colour in males. In general, the colouration of males becomes more intense during the annual rut, with the coat becoming much paler, almost white, contrasting with the darker patterns on the face and legs.
The males have long, curved-back horns that typically measure 54 to 60 cm (21 to 24 in) in length. The horns are slender, with ring-like ridges on their lower portions and smooth, pointed, tips. Although the horns are relatively uniform in length, there is some variation in their exact shape, so the distance between the tips can be quite variable, ranging from 19 to 46 cm (7+1⁄2 to 18 in). Unlike caprines, the horns do not grow throughout life. The ears are short and pointed, and the tail is also relatively short, at around 13 cm (5 in) in length.
The fur of Tibetan antelopes is distinctive, and consists of long guard hairs and a silky undercoat of shorter fibres. The individual guard hairs are thicker than those of other goats, with unusually thin walls, and have a unique pattern of cuticular scales, said to resemble the shape of a benzene ring.