Estrogens, GH and IGFs are essential in the development and growth of the skeleton and for the maintenance of bone mass and density. Treatment of precocious puberty with GnRH analogs (GnRHa), by reducing sex steroid levels, leads to a situation of hypoestrogenism that may theoretically have a detrimental effect on bone mass during pubertal development. A reduction in bone mineral density (BMD) during GnRHa treatment has been demonstrated, but GnRHa treatment in patients with central precocious puberty (CPP) does not seem to impair the achievement of normal peak bone mass (PBM) at final height. However, calcium supplementation is effective in improving bone densitometric levels and may promote better PBM achievement. In children and adolescents with GH deficiency (GHD), BMD assessed by dual-energy X-ray absorptiometry (DEXA) and bone turnover are significantly reduced, but they are stimulated by GH treatment. GH treatment leads to improved bone density, function of the dose and duration of treatment, and patients may require prolonged GH treatment beyond the time of growth to improve PBM. After the discontinuation of GH therapy, the more active population had higher bone mineral content (BMC) levels than patients with low physical activity. In our experience, the therapeutic association of GH and calcium also represents a valuable tool in pursuing a proper BMC in GHD patients. We concluded that nonhormonal factors, such as physical activity and nutritional factors, are important in determining bone metabolism and bone mass.