All extant species have the same body plan, but there are wide variations in size (from the 5 kg Philantomba species to the 80 kg yellow-backed duiker, Cephalophus silvicultor) and extreme variations in colors and markings (as evidenced by common names: red duiker, blue duiker, black duiker, gray duiker, white-bellied duiker, yellow-backed duiker). There is minimal sexual dimorphism, but (unusual in mammals) females tend to be larger than males. In the majority of species, both males and females grow horns (except for Philantomba, Sylvicapra, and Cephalophus rufilatus). The horns are among the smallest of any bovid; their small size, low angle, and position near the back of the skull reduces the chance of them becoming caught in jungle underbrush. A tuft of hair on the forehead often conceals these tiny spikes. Duikers tend to be territorial - their very large preorbital glands are used in scent marking. The glands form prominent bulges on either sides of the nose, opening into a long slit which extends well in front of the eyes.

Duikers have a virtual monopoly on frugivory in African rainforests, but even so, several species of duikers have been recorded eating meat. Their brains are large and complex; since duikers are reliant on fallen fruits, most species are aware of canopy activity, and will often follow primates in order to eat dropped leftovers.