The CC chemokine eotaxin is a selective chemoattractant for eosinophils in vitro and induces eosinophil migration in vivo. Here we show that the mouse orphan receptor previously named macrophage inflammatory protein-1 alpha receptor-like 2 is a functional eotaxin receptor. For consistency with other nomenclature, we have renamed the receptor mouse CC chemokine receptor 3. Human and mouse eotaxin, but not other chemokines, induced transient increases in [Ca2+]i in human embryonic kidney 293 cells expressing the receptor. RNA for the receptor was abundant in primary eosinophils, but at low levels in neutrophils and macrophages. These properties make this receptor the best known candidate to mediate mouse eosinophil responses to eotaxin.