Objective To clarify the determinative role of lean mass(LM)and fat mass(FM)on geometric indices of the hip bone strength in healthy postmenopausal women.Methods A cross-sectional study was performed.One hundred and one healthy postmenopausal women,ageing from 48.8 t0 82.6 years old,were involved.Bone mineral density(BMD)of the femoral neck(FN_BMD),the total hip(TH_BMD),and the proximal femur was detected using dual energy X-ray absorptiometry.Total FM and total LM were derived from the whole body scan.Multivariate linear regression models were used to assess the relationship.R esults In univariate analysis,there was a significant negative correlation between advanced age,years since menopause and FN BMD,TH_BMD,and the hip geometric parameters(CT,CSA,SM,and SI)(P < 0.05 for all).Height,body weight,FM and LM had a positive relationship with bone data.In multiple liner regression analysis,both LM and FM were significant predictors of the hip BMD and hip structural geometric properties after controlling of age,height,years since menopause.However,when both LM and FM were included in the multivariate regression model after controlling for confounders above,the relationships between LM and bone data disappeared.Only FM was an independent predictor for bone mass and hip strength(P <0.001 for all).Variation explained by FM for FN_BMD,TH_BMD,and hip strength parameters(CT,CSA,SM,and SI)was 19.9%,16.1%,31.3%,30.3%,34.0%,and 24.4%,respectively.Conclusion These data suggest that FM,rather than LM,is independently associated with measures of the proximal femur strength in healthy postmenopausal women.