The rationale for and indications of calcium supplementation remain unclear. Based on available studies, the authors discuss the role of calcium supplements for the prevention of type I osteoporosis, which mainly manifests as vertebral crush fractures 15 to 20 years after cessation of menses. Although not the most effective treatment, calcium supplements may be of value especially 5 to 20 years after menopause, when hormone deficiency is no longer the main cause of bone loss.