Osteoporosis represents reduced amount of bone mass per unit volume as compared with controls of the same age and sex. The purpose of this study was to show how bone mineral densities of spine and intertrochanteric area decrease with aging, to investigate the relationship between the bone mineral densities (BMD) of the two areas, and to obtain fracture threshold values. We measured BMD of lumbar vertebrae and intertrochanteric areas by Dual Energy X-ray Absorptiometry (DEXA) from 241 postmenopausal women. 190 normal postmenopausal women comprised non-fracture group and there were 50 fresh thoracolumbar fracture patient and 31 intertrochanteric fracture patients in whom the fractures were not caused by high energy trauma. The mean bone mineral density values of non-fracture group were significantly higher than those of fracture groups and significant correlation held between bone density of spine and that of intertrochanteric area in non-fracture group and fracture groups. The fracture threshold was 0.837 g/cm3 in spine fracture group and 0.792 g/cm³ in the intertrochanteric fracture group.