Dual-energy x-ray absorptiometry (DXA) is an established method for estimating bone mineral density (BMD) of the lumbar spine. In a prospective study, the sensitivity of BMD measurements between anteroposterior and lateral projections were evaluated in 204 postmenopausal women based on their DXA analysis. Patients were divided into two groups according to the absence or presence of lumbar scoliosis. Lateral projection DXA measurements were more sensitive than AP projection measurements for early detection of bone loss in postmenopausal women. Lateral projection DXA analysis is not recommended in spines with lumbar scoliosis.