Osteoporosis and osteopenia diagnosed in developmental age require special treatment with careful consideration of indications for particular drugs, their dosage and monitoring of treatment. The classical method, similarly as in adults, is administration of calcium and vitamin D, physical rehabilitation, treatment of fractures and pain release. The aim of the study was to evaluate the effect of combined therapy of decreased bone mineralization in 45 children (28 boys and 17 girls) aged 6.5 to 18 years. In 15 of them secondary osteoporosis (13/15) or osteopenia (2/15) were diagnosed, and in 30 cases the disorders were primary -16/30 and 14/30, respectively. The patients were treated from 6 months to 4 years. All patients received calcium and vitamin D preparations. In the majority of treated children calcium-rich diet and physical rehabilitation were applied, adjusted to the advancement of the disease. In 6 cases treatment with bisphosphonates was given. In our study we also present results and observations from calcitonin treatment of 35 children aged 6 to 18 years. This treatment was applied during the last 5 years in various periods--in 23 children with secondary and in 12 with primary osteoporosis. The therapy of osteoporosis and osteopenia in developmental age should always be individually assessed to disease advancement, symptoms, concomitant illnesses, age and possibilities of long-term treatment. The classical treatment includes appropriate intake of calcium, vitamin D and other vitamins and minerals (pharmacological preparations, diet), physical rehabilitation and pain release. On the basis of our observations it appears that antiresorptive drugs such as calcitonin and bisphosphonates may be used in treatment of osteoporosis in developmental age. Evaluation of treatment efficacy should involve clinical improvement and results of additional examinations, especially densitometry. Among biochemical tests, bone resorption markers (Pyr, Dpyr, CrossLaps) appeared to be the most useful; treatment of bone fractures should be evaluated by X-ray examinations.