Osteopenia, term of child pathologies, is a decrease in bone mass relative to chronological age, being an intermediate state between normal bone mass and osteoporosis. It has multiples etiological factors, comprising a heterogenic group of diseases of the connective tissue with genetic determinism and osteopenia gained in various pathological conditions affecting bone homeostasis. Early diagnosis is determined by measuring bone density through non invasive imaging methods, the most common being dual-energy x-ray absorptiometry (DEXA) and quantitative ultrasonography. Treatment in children customize through the need to adapt the intake of calcium and vitamin D to physiological growth needs and to requirements of some diseases. Specific drug treatment with nitrogen bisphosphonates was introduced to the children but is not yet well acted. Attention to be given to this bone pathologies in children and adolescents is warranted of its prognostic value for the rest of his life, to the peak bone mass of 20-21 years of age.