To study the relationship between estrogen gene polymorphism and TCM Syndrome Differentiation of female postmenopausal osteoporosis in China.Two hundred and forty-six Chinese postmenopausal women, age 44-80 years, mean 65.8 years, using molecular biological method to analyze the endonuclease Pvu II, Xba I restriction fragment length polymorphisms (RFLPs), with dual X-ray bone mineral density absorption meter to determine the bone mineral densities of lumbar vertebra (L1-4) and femur (intertrochanter, femur neck, Ward's region) separately. The subjects were divided into Kidney Yin deficiency type, Kidney Yang deficiency type and both Kidney Yin-Yang deficiency type, to observe the relationship between TCM and bone density as well as estrogen receptor gene polymorphism, Pp(Pvu II) and Xx(Xba I) were used to express RFLPs, the capital P and X to express the deficit of restricting sites.Bone mineral density of PPxx gene type (n = 21) was obviously lower than that of other gene types (n = 225), lumbar (-0.71 +/- 0.46) g/cm2, intertrochanter (-0.31 +/- 0.58) g/cm2, femur neck (-0.84 +/- 0.66) g/cm2, Ward's region (-0.96 +/- 0.85) g/cm2, the TCM Syndrome Differentiation typing of this gene type belonged to both Kidney Yin-Yang deficiency type.Estrogen receptor gene RFLPs is related to TCM Syndrome Differentiation typing.