Our purpose is to bring a contribution to a better understanding of the role played by the condylar cartilage in children's mandibular growth. In the newborn, microradiographical analysis of frontal (fig. 1, 2 and 3 A) or sagittal sections (fig. 4 A) has been used to locate trabecular bone of endochondrial origin. This trabecular bone contains islets of calcified cartilage easy to identify in the microradiograph (fig. 3 B) or in the section itself after methylen blue staining (fig. 4 B) and resulting from the activity of the condylar cartilage (fig. 4 C). At four month of age, the condylar cartilage is still in activity (fig. 5 A and 5 B). From both morphological and physiological points of vue, this work leads to suggest that the condylar cartilage must be compared to a growing epiphyseal nucleus or to a so-called infertile extremity of a small long bone rather than with a true growing cartilage.