Abstract: Objective To investigate the bone mineral density(BMD)of lactating women with different ERPvu Ⅱ and Xba Ⅰ genoty pes and to analyse the main influential factors of BMD.Methods 101 healthy lactating women of Han nationality in Wuhan were selected in the study.The ERP vu Ⅱ and Xba Ⅰ genot ypes were determined by PCR-RFLPs.The BMD of lumbar spine and lefthip were measured by dual-energy X-ray absorpt ionmetry.Calcium intakes were calculated from a 3 day food consumption questionnaire.Results The osteoporosis rate of 101 lactating women was 201 8%.The mean BMD values of the PPxx genotypes were lower than that of the other five genotypes,but there was no significant difference between them.The bone loss rate of troch was significantly higher than that of other sites(P=0.002).Calcium intake,Body Mass I ndex(BMI),lactating time were significantly related to lumbar spine BMD via multiple linear regression(the standar dized coefficients were 0.242,0.236 and-0.192,respectively and Pvalues were 0.014,0.017 and 0.047,respect vely).Conclusion Some variation of the ER gene links to the descent of BMD,especially in PPx x genotype.Troch BMD monitoring is propitious to find early bone loss of lactating women.To give systematic calcium supplementary to lactating women can prevent the bone loss and osteoporosis.