The commonest secondary cause of osteoporosis is Glucocorticoid-induced osteoporosis (GIO) which is also the commonest cause of iatrogenic osteoporosis. Chronic glucocorticoids (GCs) treatment may cause fractures in 30-50% of patients. Fracture risk is increased among those using oral glucocorticoids. On long-term glucocorticoids therapy, deterioration of cortical bone progressively detected and long bones became increasingly fragile. Any patient with chronic glucocorticoids therapy should be expected as suffering from GIO. Patients on glucocorticoids should receive supplementation with calcium. These deleterious influences are the result of suppression of bone formation that occurs with an early but temporal rise in the process of bone resorption. Numbers of osteoclast also rapidly rise, and accompanied by inactivation of osteoblast and decline of bone formation, these changes cause the fastest bone loss during the initial phase disease. Glucocorticoids cause inhibition of osteoblasts replication and function and accelerate their apoptosis. Calcium is fundamental for bone, and assuring sufficient calcium intake is important. It is said that when children and adolescents ingest large amount of calcium could result in a decrease in the danger of developing osteoporosis when they got old, however, some researches propose that solitary use of calcium supplementation might not be enough for lowering the danger for fracture. Conflicting results were reported about the effects of the use of supplemental calcium on the bone mineral content in those taking glucocorticoids therapy. Whereas, calcium supplementations were used in most bone protective treatment trials and therefore should be used as an adjunct to GIO therapy.