We have provided a most update national reference database about me peak bone mass(peak bone mineraldensity,PBMD)and reference plot of BMD at vertebral and hip sites is established based on the largest sample(n-7059)and a prospective investigation in Mainland Chinese male and female using DXA from 2001-2005 SO far,which willimprove investigation of prevalence and rational standard for nationwide osteoporosis prevention and treatment.Introduction This study was carried out to establish national reference database about the peak bone mass(peak bone mineral density,PBMD)and reference plot of BMD in Mainl and Chinese male and female.Materials and Methods A total 7059 subject aged 20-89 years old who participated in the national reference database study on PBMD and reference plot of BMD using DXA from 2001-2005.Among them,a total 4067 healthy young volusteers(2034 in male and 2033 in female)were enrolled in tbe study for determination of PBMD.All subjects in the study were distributed over 9 provinces located the eastern,southern and northern,middle regions,and where reons in whole mainland China.Two different instrument programs,Hologic and Lunar,with European spine phantom(ESP)for cross-calibration were performed in the study.The BMD(mean±Sdlin each 5 age group was calculated and corrected by ESP,and the highest mean BMD in that age group was defined as the PBMD (cross-sectional PBMD as a function ofage).The cubic equation of the best regression model was also determined from the curve-fitting of the calculations of age-relatedBMD.