To verify the functional hypotheses that link, in vertebrates, the skeletal mass (Ms) to the total body mass (Mt), the skeletons of 75 adult specimens of anuran amphibians (Mt = 5–400 g) belonging to 7 species, aquatic, semiaquatic, or terrestrial (5 Rana, Bufo americanus, and Xenopus laevis), have been extracted by enzymatic maceration, and air-dried. Covariance analyses show significant differences in position, but not in slope, between the anuran species in the specific allometric relationships [Formula: see text]. A Spearman rank test indicated a highly significant relationship between the regression-line position and the level of species infeodation to the aquatic habitat. The relationship is more evident for the Ranids. The relative mass of the skeleton in terrestrial species (e.g., R. sylvatica: 4.4%) can be twice that of aquatic species (e.g., R. septentrionalis: 2.3%). For the 75 anuran specimens, the calculated allometric equation, [Formula: see text], is very close to the one already established for teleost fish. When R. septentrionalis is excluded, the allometric coefficient becomes significantly inferior to unity (b = 0.928). It is concluded that the relative mass of the skeleton is linked with individual and species body size but that the life mode has a preponderant influence. A model that takes into account intra- and inter-specific variations in body mass is developed to predict the skeletal mass of an anuran.