Raloxifene reduces the risk of new vertebral fractures, but its effect on the severity of these new fractures has not been determined. The MORE (Multiple Outcomes of Raloxifene Evaluation) trial studied the effects of placebo, raloxifene 60 or 120 mg/day in 7,705 postmenopausal women with osteoporosis. Radiologists assessed new vertebral fractures from radiographs and graded the fracture severity as normal (no fracture) or mild, moderate or severe. New clinical vertebral fractures were defined as new vertebral fractures associated with symptoms, such as back pain, and confirmed in radiographs. In the total study population, the majority (76.4%) of the women who experienced clinical vertebral fractures were diagnosed with new moderate/severe vertebral fractures. In turn, women with moderate/severe vertebral fractures in the overall population were more likely to experience clinical symptoms suggestive of fracture than were women who had new mild-only vertebral fractures. The incidence of new mild-only and moderate/severe fractures was the same in women without prevalent vertebral fractures, but the incidence of new moderate/severe fractures was 2 to 3 times higher than that for new mild-only fractures in women with prevalent vertebral fractures. Raloxifene 60 mg/day decreased the risk of at least 1 new moderate/severe vertebral fracture by 61% in women without prevalent vertebral fractures [RR 0.39 (95% CI 0.17, 0.69)], and by 37% in women with prevalent vertebral fractures [RR 0.63 (95% CI 0.49, 0.83)] at 3 years. The risk reductions for at least 1 new moderate/severe vertebral fracture were not significantly different between the raloxifene doses, in women with and without prevalent vertebral fractures. The effects of raloxifene on significantly decreasing the risk of new moderate/severe vertebral fractures may explain the risk reduction for new painful clinical vertebral fractures observed with raloxifene, and is particularly important in postmenopausal women with severe osteoporosis who are at higher risk for moderate or severe fractures.