The intended task of the present study is to shed some light on the main characters, stratigraphical distribution and possible ways of life of the Western European representatives of the genus Hippopotamus, namely Hippopotamus antiquus Desmarest (= H. major Cuvier), H. amphibius L. and H. tiberinus Mazza. The investigation includes also comparisons with H. gorgops Dietrich, an African representative of the stock from which some European hippopotamuses are supposed to have derived. Basing on a whole series of observations, the present author believes that among the specimens attributed to H. incognitus Faure, the oldest ones, as those from Durfort, should actually be attributed to H. antiquus, while the others, more recent, as those from Barrington, should rather be assigned to H. amphibius. Since the specimens from Barrington are the type material of H. incognitus, in the writer's opinion the latter inevitably falls in the synonymy of H. amphibius. Hippopotamuses first dispersed in Europe during the Early Pleistocene, where they are represented by H. antiquus. This species apparently became extinct shortly before the beginning of the Elsterian. H. tiberinus, a probable offspring from the Antiquus stock, is first attested during the interval straddling the Villafranchian-Galerian transition. In the course of the Middle Pleistocene it dispersed in Central Europe, from which it apparently disappeared at the beginning of the Saalian, withdrawing to more southern areas. Hippopotamuses are apparently missing from northern and central Europe during the latest Middle Pleistocene, surviving in Italy. With the climatical amelioration which marked the transition to the Late Pleistocene, H. tiberinus returned to Central Europe, dying out definitely before the beginning of the last glaciation. H. amphibius made its entrance in Europe in the course of the Eemian and moved away during the first part of the first Pleniglacial. Concerning the habits of life of these animals, H. amphibius spends a considerably long time out of the water roaming even quite far in search of food. H. antiquus and, even more, H. gorgops and H. tiberinus, on the other hand, seem to have had more aquatic habits, in that they likely spend most of their time immersed in water, grazing mainly on water plants and vegetation ashore, and perhaps only occasionally left the water looking for food on land. Although hippopotamuses are usually relegated to play the role of second actors compared with other more 'noble' faunas, they may often be very indicative forms from both stratigraphical and paleoecological points of view.