Radiographic and histologic examination of long bone epiphyses in 25 species of Varanoidea (including one Heloderma species) reveals a qualitative difference in epiphyseal development between small and large species. In small monitor lizards, most of them belonging to the subgenus Odatria, metaphyseal plates tend to disappear completely, with fusion of primary and secondary epiphyseal ossification centers in adults that reach an individual body length close to the maximum known for their species. Epiphyseal fusion results in a complete and irreversible arrest of growth. This observation falsifies the previously accepted conclusion that the monitor lizards as a whole have a continuous growth. Conversely, in larger species, morphologically complete growth plates remain present in most (but not all) specimens, including very large adults. Although this feature is not firm evidence of a continuous growth, it nevertheless suggests that large species maintain active growth during ontogeny over a longer period than small species.