The purpose of this study was to examine the effects of dietary caffeine supplementation on bone mineral density and bone mineral content in ovariectomized rats. Twenty eight female Sprague-Dawley rats (body weight $210;{pm};5;g$) were divided into two groups, ovariectomy (OVX) and Sham groups, which were each randomly divided into two subgroups that were fed control and control supplemented with caffeine diets (caffeine 0.03% diets). All rats were fed on experimental diet and deionized water ad libitum for 6 weeks. Bone mineral density (BMD) and bone mineral content (BMC) were measured using PIXImus (GE Lunar Co, Wisconsin) in spine and femur. Serum alkaline phosphatase activity (ALP) and osteocalcin and urinary DPD crosslinks value were measured as markers of bone formation and resorption. The results of this study indicate that body weight gain and food intake were higher in OVX groups than in Sham groups regardless of diets. There were no differences weight gain between the control and caffeine groups in both OVX and Sham groups. Within the OVX groups, serum Ca concentration was lower in rats fed caffeine than in rats fed the control diet. Serum ALP, osteocalcin, urinary Ca, and phosphate were not different in each group. Spine BMD, spine BMD/weight, and spine BMC/weight, femur BMD/weight and femur BMC/weight of ovariectomy groups were significantly lower than Sham groups. Within the OVX group, there were no differences in spine BMD and BMC and femur BMD and BMC. These results indicate that no significant differences in spine and femur BMD were found due to 0.03% caffeine intakes in diet in OVX rats for 6 weeks. No negative effect of caffeine in 0.03% diet on bone mineral density were found in the present study. Further investigation of the relation between caffeine and bone mineral density are warranted. (KoreanJNutr2008; 41(3): 2l6~223)