Abstract Fossil dolphins belonging to the extinct family Kentriodontidae are small to medium-sized toothed cetaceans, which probably include the ancestors of some living species. Kentriodontids are known from rocks of Late Oligocene to Late Miocene age in various parts of the world. Among kentriodontids, species in the subfamily Kentriodontinae (e.g. species of Kentriodon Kellogg, 1927) are the most ubiquitous and generalized; these are now known from latest Oligocene to earliest Miocene strata in New Zealand and Patagonia, and Middle Miocene deposits in Maryland, Virginia, California and Japan. The diversity, morphologies and distributions of Miocene species of Kentriodontinae seem to parallel those of the living species of mostly pelagic delphinids in the subfamily Delphininae, and the fossil group may have been an ecological or behavioral/functional counterpart of the latter. Kentriodontines are inferred to have been wide-ranging neritic to pelagic animals that ate small fish and other nectonic organisms; they were probably active echolocators, and might have formed large schools. They are relatively common as fossils and, therefore, are potentially useful for intercontinental correlations of marine deposits.