河马科（学名Hippopotamidae）是臼齿下目仅有的一科，大型偶蹄目。现存仅有河马和倭河马两种，都生活在非洲。

This is the article on the family Hippopotamidae; for the main article on hippos, see Hippopotamus

Hippopotamuses are stout, naked-skinned, and amphibious artiodactyl members (and the only living members) of the family Hippopotamidae possessing three-chambered stomachs and walking on four toes on each foot. While they resemble pigs physiologically and are pseudoruminants like camels, their closest living relatives are actually the cetaceans (whales and dolphins).