BACKGROUND: In general, increased body weight may be a risk factor for hypertension, diabetes, hyperlipidemia, and coronary heart disease. It is very difficult to lose weight especially in aged people. Osteoporosis is commonly developed in aged. Many reports revealed that obesity may prevent bone loss. The protective effect of obesity on bone has been ascribed to a high body fat content. Obese aged people can be very confused whether to decide to lose weight or not. METHODS: We evaluated 137 women aged over 60 who visited a health care center of a university hospital in Seoul from Jan. 1999 to Oct. 1999 to determine the effects of obesity on bone mineral density in aged Korean women. We measured anthropometrical characteristics, BMD of lumbar spine, markers of bone turnover, and FSH of the subjects. RESULTS: The results revealed that obese group had a greater BMD at lumbar spine, but the levels of FSH were noted to be lower than the non obese group. But, none of the markers of bone turnover showed significant differences between the two groups. BMI was positively correlated with BMD (r=0.455, P<0.001) by Pearson's correlation matrix. Also, the level of total alkaline phosphatase significantly had negative association with BMD. The level of FSH revealed that it had a negative correlation (r= 0.290, P<0.01) with BMI. CONCLUSION: We concluded that obesity might have a protective effect related with FSH. Prospective studies on endocrinologic association with BMD, bone markers, FSH and estradiol will be needed.