The skin contains a layer of fat, which in Hippopotamus is 50 mm thick. The short tail is rather bristled. The foot bones are separate. The terminal digital bones have nail-like hooves. The stomach is complex and three-chambered but nonruminating.
Females have two mammae.
The large skull has an elongate facial region, but the braincase is relatively small. There usually is only one pair of lower incisors in Choeropsis but two or three pairs in Hippopotamus. The incisors and canines are tusklike and grow continuously. The incisors are rounded, smooth, and widely separated. The upper incisors are quite short and project downward.