Background A number of studies have examined the association between estrogen receptor alpha (ESR-α) gene polymorphisms and bone mineral density (BMD),but previous studies of ESR-α gene Xbal (rs9340799) and Pvull (rs2234693) polymorphisms have been hampered by small sample size,regional restrictions and inconclusive results.Thus a meta-analysis is needed to assess their pooled effects.üMethods This study reviewed all published articles indexed in Pubmed using the keywords in the title or abstract.All data were extracted independently by two reviewers using a standard form,the studies were mete-analyzed and minor discrepancies were resolved by authors' discussion.Results Twenty seven eligible studies involving 8467 women and 2032 men were identified.The Xbal and Pvull polymorphisms were significantly associated with BMD of the lumbar spine.XX and PP homozygotes had a protective effect in comparison with carriers of the x and p alleles,the effects were more significant in premenopausal women or Western women.At the femoral neck,the results were different.XX served as a protective factor in postmenopausal women,Western women,Western postmenopausal women,and men,while PP was likely to serve as a risk factor in Eastern women,Eastern postmenopausal women,and men.Conclusions The Xbal polymorphism is correlated to BMD at diverse skeletal sites.PP had a protective role for the lumbar spine but might be a risk factor for the femoral neck.