Vitamin D deficiency is a highly prevalent condition in approximately 30% to 50% of the general population even in tropical countries. Sufficient level of this vitamin is important not only for maintenance of bone health and calcium metabolism but also in reducing the risk of many extra skeletal diseases. Vitamin D deficiency is associated with excess mortality in the general population as well as in patients with cardiovascular disease. The impacts of vitamin D on bone mass vary according to life-stages and ranges from bone mass attainment during the adolescence period to bone mass preservation as well as fracture prevention throughout the peri menopausal and postmenopausal periods. Insufficient levels of serum vitamin D impair adequate attainment of peak bone mass and reduce bone mass acquisition and maintenance.