Yellow-backed duikers have a convex body shape, standing taller at the rump than the shoulders. They have very short horns, 8.5 to 21 cm (3.3 to 8.3 in) in length, which are cylindrical and ribbed at the base. An orange crest of hair can be found between their horns. Yellow-backed duikers get their name from the characteristic patch of yellow hairs on their rump, which stand when the duiker is alarmed or feels threatened. Yellow-backed duiker females often grow to be slightly larger than males. Coloration is very similar between sexes and very little sexual dimorphism exists. The head-and-body length is 115 to 145 cm (45 to 57 in), with a short tail measuring 11 to 18 cm (4.3 to 7.1 in). The yellow-backed duiker weighs in at about 60–80 kg, making it the largest of its genus. It has a large mouth, throat and jaw musculature.