Sometimes called "mouse deer" due to their tiny stature, chevrotains are the smallest extant ungulates, never weighing over 20 kilograms (adults of the genus Tragulus may weigh less than 1.5 kg). Most members of the Tragulidae inhabit tropical forests in southeast Asia, but a single species is found in central and western Africa; all species feed mainly on grasses and leaves from the forest floor. Physically, chevrotains resemble other small forest-dwelling herbivorous mammals such as the South American agouti (Dasyproctidae, Rodentia) and African duikers (Cephalophinae, Cetartiodactyla), with forward-sloping shoulders and powerful hind quarters.

The fossil record of chevrotains begins in early Miocene deposits in Europe, where they persisted until the early Pliocene. Chevrotains spread to Asia during the Miocene, and the majority of species still inhabit the southeastern portion of this continent. The Tragulidae are known in Africa from fossils from the early to middle Miocene, but do not reappear in the African fossil record until the Pleistocene. There are three modern genera and eight species. Recent taxonomic revisions of the Tragulidae have split the two former species of the genus Tragulus (T. napu and T. javanicus) into six species; as no studies on the relationships within this revised genus have been performed, the family tree (below) is still incomplete.

Four digits are present on each foot, but the second and fifth digits are short and slender. The stomach has four chambers (like the rest of the ruminants), but the omasum is rudimentary. The skulls of tragulids are small (condylobasal length is less than 10 cm). In males, the upper canines form tusks which protrude downwards from the mouth. The lower canines resemble incisors. The dental formula is I 0/3, C 1/1, P 3/3, M 3/3 x 2 = 34. There is a unique plate of bone to which the sacral vertebrae attach.