BACKGROUND: Osteoporosis is easily seen in postmenopausal women. The bone loss situation is different among populations of different age and body mass.OBJECTIVE: To analyze the effects of age, menopausal duration,menopause age, height, body mass and body mass index on bone mineral density (BMD) in postmenopausal women.DESIGN: Random sampling test was conducted to postmenopausal women.SETTING: A clinical trial center of a provincial Chinese traditional medicine research institute, an orthopaedic department of a university hospital and a bone wound department of a university.PARTICIPANTS: Totally 603 naturally postmenopausal women in Fuzhou area from September 2000 to August 2003.METHODS: Random sampling method was used. The age of participants,menopausal duration, menopause age, height, body mass and bone mineral index(BMI) were recorded. Dual energy X-ray bone mineral density machine was used to examine the bone mineral density of lumbar, neck of femur, great trochanter and Ward' s area while SPSS software was used to conduct regression analysis.MAIN OUTCOME MEASURES: The correlation between age,menopausal years, menopause age, height, body mass, BMI and bone density as well as the regression equation.RESULTS: There was very significant correlation between age, menopausal duration, body mass, BMI of postmenopausal women and bone mineral density of lumbar, neck of femur, great trochanter and Ward' s area. The BMD in low body mass group is greatly lower than that of obesity group( P ＜ 0.01 ). The main factors impacting BMD of lumbar are in turn age, body mass and menopause age while the regression equation: y = 0. 927 - 0. 0093 X1+ 0. 0037X2 + 0. 004X3. The factors impacting BMD of neck of femur are in turn menopausal duration, body mass, menopause age and the regression equation was: y = 0. 687 - 0. 0081 X1 + 0. 0048 X2 - 0. 0034 X3. And the factors affecting BMD of greattrochanter are age, body mass and menopause age while the regression equation was y = 0. 591 - 0. 0038 X1 + 0. 0042 X2 - 0. 0024 X3. Age, body mass index and menopausal duration are main factors affecting BMD of Ward' s area and the regression equation was y =0. 686 -0. 0072 X1 +0. 0136 X2 -0. 0046 X3.CONCLUSION: The BMD of lumbar and hip gradually decreases with the increase of age in postmenopausal women. The risk of getting osteoporosis in people with low body mass is greater than women in normal body mass groupand obesity group.