This chapter reviews the clinical areas of interest, the possible applications, and limitations of using markers in the pediatric setting. Biochemical markers of bone metabolism are compounds that are released from bone tissue into the circulation and can be quantified in serum or urine samples. In adults, bone turnover markers mainly represent bone remodeling and are commonly used as independent predictors of the risk of osteoporosis and fractures, to monitor antiresorptive therapy and also have a promising role in metastatic bone disease. In children, these markers are released into the circulation during three different physiological processes: growth in bone length (bone elongation); growth in bone width (bone modeling by periosteal expansion); and bone remodeling (turnover). All bone markers measured in children reflect the sum of these three processes.