OBJECTIVE: To investigate the relationship between body fat distribution and bone mineral density (BMD). METHODS: Subjects were 282 premenopausal women (mean age +/- standard deviation [SD], 38.8 +/- 8.5 years; range, 20-51 years) with regular menstrual cycles. Baseline characteristics included age, age at menarche, height, weight, body mass index ([BMI], weight/height(2)), and parity. Anthropometric characteristics including the ratio of trunk fat mass to leg fat mass (trunk-leg fat ratio), percentage of body fat, and total body lean mass were measured by whole-body scanning with dual-energy x-ray absorptiometry. Lumbar spine BMD (L2-4) was also measured by dual-energy x-ray absorptiometry. Correlations of BMD to baseline and anthropometric characteristics were investigated using univariate and multivariate analysis. RESULTS: Although height, trunk-leg fat ratio, and total body lean mass were positively correlated with lumbar spine BMD (r =.18, P <.01; r =.17, P <.01; and r =.25, P <.001; respectively), age at menarche was inversely correlated with BMD (r = -.19, P <.01). On multivariable analysis, trunk-leg fat ratio, height, age at menarche, and total body lean mass were still independently correlated with lumbar spine BMD (P <. 05). However, total fat mass was not correlated with BMD. CONCLUSION: Upper body fat distribution rather than overall adiposity is associated with lumbar spine BMD in premenopausal women. Humoral factors associated with body fat mass appear to influence lumbar spine BMD.