Yellow-backed duikers are short-legged, hunchbacked members of the antelope family. Their head is long and wedge-shaped with a light grey muzzle and white lips. They have small ears, as well as small eyes, which have a maxillary or pre-orbital gland below that is used for scent marking their territory. It secretes a black, sticky or yellow, waxy substance with a strong, musky odor. Males and females are about the same size and both have slightly curved horns that are three to eight inches long. They share similarities with other duikers, but are distinctive because of their large size and the yellow patch of long hairs on their rump, which contrasts against their dark brown, short, glossy coat. When they are alarmed, yellow-backed duikers raise these hairs. They are the biggest of the 15 duiker species.