We describe 3 cases of toddler's fracture of the tibia that were diagnosed via sonographic examination. In cases, initial radiographs did not show the fracture, whereas sonographic examination revealed a layer of low reflectivity superficial to the tibial cortex and an elevated periosteum, suggesting a fracture hematoma. The diagnosis was confirmed at 2-3 weeks with radiographs demonstrating periosteal reaction. Both fractures were treated with cast immobilization for 4 weeks and made a full recovery. The third case was diagnosed via sonography and was confirmed by the initial radiographs. These results strongly suggest that sonography can detect the presence of a fracture hematoma and thus may help diagnose this injury earlier.