The objective of the study was to determine whether or not U.S. normal data for female Vertebral Bone Mineral Density is suitable for use in an Irish population. One hundred and fifty-six healthy Caucasian women of permanent Irish domicile had bone densitometry performed using single energy quantitative computed tomography of L2, L3 and L4 vertebrae. We found that comparison of our results to normal American data shows a slight and progressive increase in bone mineral content of postmenopausal American women with age relative to the Irish population. This difference is small and not sufficient to justify development of separate normal values for Irish women. We conclude that this discrepancy may be due to a combination of environmental and racial factors or to the more rigorous exclusion criteria applied in our study.