The habit of certain creatures, or organisms, to feed on blood.

Some intestinal nematodes, such as the Ascaris, feed on blood extracted from the capillaries of the gut and many species of leeches are examples of hematophagous creatures.

Some fish; such as, lampreys, and certain mammals, especially the vampire bats, also practice hematophagy.

Among the hematophagous insects of medical importance are the sandfly, blackflies, tsetse flies, bedbugs, assassin bugs, mosquitoes, ticks, lice, mites, midges, chiggers, and fleas.