Decreased bone density and increased fracture risk are seen in patients with spinal cord injury. The bone resorption rate is markedly increased. Hypercalciuria, low PTH, and low l,25(OH)₂ vitamin D are commonly seen. Bedrest studies show similar findings but of lesser magnitude. Therapies to treat or prevent osteoporosis include optimal nutrition (with care to avoid exacerbating hypercalciuria), and weight-bearing or functional electrical stimulation. Cycle ergometry may prevent some bone loss, especially in acutely injured patients. Estrogen should be considered in women who are postmenopausal or who have amenorrhea, but not if they are at high risk for thromboembolism. More research on the effects of estrogen on this population is needed. Bisphosphonates also may help prevent acute bone loss; oral routes must not be used in recumbent patients. Thiazides could be a useful adjunct therapy.