Idiopathic renal calcium stone disease often presents with reduced bone mineral content. Investigations using non-invasive methods for the measurement of bone mineral content (single and dual-photon absorptiometry, dual-energy x-ray absorptiometry, quantitative computed tomodensitometry) show a slight decrease in skeletal mineral content of idiopathic renal stone formers (RSFs). The alterations in bone mineral content in RSFs have different explanations: prostaglandin-mediated bone resorption, subtle metabolic acidosis and 1-25 vitamin D disorders. Bone mineral content is worsened by insufficient dietary calcium leading to a negative calcium balance.