The effects of dietary supplementation with cheonggukjang containing arrowroot isoflavones (AIC) on bone mineral density and bone metabolism were investigated in 6-week old ovariectomized Sprague-Dawley rats divided into 4 groups: sham (sham-operation and basal diet), OVX (ovariectomy and basal diet), OVX+C (ovariectomy and basal diet with 5% cheonggukjang), and OVX+AIC (ovariectomy and basal diet with 5% AIC). Eight weeks following ovariectomy, body weight gain, and serum alkaline phosphatase activities were significantly reduced in OVX+C and OVX+AIC. Serum osteocalcin levels were significantly lower in OVX+AIC. Although urinary calcium, phosphorus, and creatinine levels increased after ovariectomy, they decreased in OVX+AIC. Bone mineral densities decreased in OVX but significantly enhanced after C and AIC supplementation. Bone mineral content did not significantly differ between OVX+AIC and sham. Thus, these results suggest that AIC may prevent bone loss in OVX rats.