The aim of this study was to assess the usefulness of bone-specific alkaline phosphatase (BALP) and the extracelluar domain of human epidermal growth factor receptor 2 (ECD/HER-2) measurements in pediatric patients with osteosarcoma as prospective prognostic and predictive markers for monitoring the treatment and early detection of disease recurrence. This evidence concerns the gene ERBB2 and osteosarcoma.