It is recommended that country-specific reference data are used when estimating diagnostic and therapeutic thresholds in osteoporosis. This study estimated normative BMD and TBS reference data for women aged 20-70 in Sri Lanka and the effect of local reference data on the diagnosis of osteoporosis among postmenopausal women. A group of healthy community-dwelling women (n = 355) aged 20-70 was recruited from Galle district in the Southern province in Sri Lanka using stratified random sampling method. They underwent DXA adhering to the manufacturer's protocol and regional BMDs and TBS of the lumbar spine were measured. The highest mean BMD in the spine (0.928g/cm2) was seen in 20-29 age group while there was a delay in achieving the peak BMD in the femoral neck (0.818g/cm2) and total hip (0.962g/cm2) regions(40-49years). BMDs showed only a mild change between 20 and 49years but a rapid decline was seen after 50years (spine 0.013, femoral neck 0.012, and total hip 0.011g/cm2 per year). The highest TBS was seen in 20-29 age group (1.371) and TBS trend with age was parallel to spine BMD. When the reference data provided by the manufacturer was used, 37% of postmenopausal women were found to have osteoporosis but this value changed to 17.6% when the local reference data were used. We found a significant difference in the prevalence of osteoporosis when the local reference values were used instead of data provided by the manufacturer. However, representative data from more centers and fracture data are required before a recommendation to use local instead of international reference data can be stated.