Nowadays there is a strong interest in the characterization of the growing process of children bone. Recent works considered osteoporosis as a pediatric disease with geriatric consequences and children are concerned by specific infantile osteo-pathologies. However, few mechanical properties of cortical growing bone are available in literature and do not yield to gold standards. The goal of this study is to evaluate the validity of ultrasonic characterization of elastic properties for growing bone. Nine surgery wastes from fibula auto-transplants (5 to 16 years old children with accordance of French ethical committee) are included in a two-step method process. A non-destructive ultrasonic evaluation (7 and 10 MHz) yields to acoustic Youngs modulus (Ea) and a micro-three point bending test yields to Youngs modulus (E). Ultrasonic testing provides an average Ea of 15.2 GPa (+/- 2.9) at 7 MHz and 15.49 GPa (+/- 3.95) at 10 MHz, and micro-flexion an average E of 10.13 GPa (+/- 5.29). A linear correlation between Ea and E is found (R2 value is 0.78 at 7 MHz and 0.79 at 10 MHz). To our knowledge, this is the highest R2 between destructive and non-destructive method found in literature for human cortical bone.