Osteogenesis imperfecta (OI) is a heterogeneous group of rare inherited bone and connective tissue disorders resulting from defect in collagen synthesis or function. It is characterized by bone fragility, which shows wide range of severities. The heterozygous mutations in the genes coding type I collagen are responsible to 80% of the OI cases. Metabolic bone markers relating type I collagen production or degraded products of mature collagen fiber may provides important information on the pathophysiology of OI. Typically, P1NP which is bone formation marker shows significant reduction and CTX or NTX shows relatively high level in type I OI. The other applications of metabolic bone markers in the management of OI will be discussed.