To assess the effect of estriol (E3) on bone loss in Japanese postmenopausal women, twenty-five women within 10 years after menopause received 2 mg/day of E3 and 2 g/day of calcium lactate (Ca) daily (n = 17; Group-E3 + Ca) or 2 g/day of Ca daily (n = 8; Group-Ca) for one year. Bone mineral density