One-year vertebral fracture risk reduction from clinical trials in adults with postmenopausal or glucocorticoid-induced osteoporosis is reviewed. Data were obtained by conducting a literature search of osteoporosis medications using the MEDLINE database, bibliographies of selected citations, and recent meeting abstracts. The methodologic quality of the trials was assessed using recently published criteria for ranking evidence. In prospective analyses, the 1-year. risk of new morphometric vertebral fractures was reduced by risedronate 5 mg/d in two 3-year studies in postmenopausal women with prevalent vertebral fracture, and in two 1-year studies in patients with or at risk for glucocorticoid-induced osteoporosis. The 1-year risk of clinical vertebral fractures was reduced by alendronate and raloxifene in post hoc analyses. Reduction of morphometrically identified vertebral fracture risk is a more stringent therapeutic goal than clinical vertebral fracture risk. Therefore, more weight should be given to data from studies that use the morphometry to assess vertebral fracture incidence.