An Advisory Group Meeting convened by the IAEA in October 1992 made recommendations on the setting up of a Co-ordinated Research Programme (CRP) using nuclear and isotopic techniques for international comparative studies of osteoporosis. The proposed CRP will be implemented by the IAEA during the period 1993-1997. The main purpose of this programme is to undertake pilot studies of bone density in selected developing country populations for the purposes of (i) determining the age of peak bone mass in each study group, and (ii) quantifying differences in bone density as functions of the age and sex of persons in the study groups, as well as quantifying differences between the study groups in different countries. The preferred technique for bone density measurements in this study is DEXA (dual energy X-ray absorptiometry). Additional measurements of trace elements in bone (and possibly also teeth) are also foreseen using neutron activation analysis and other appropriate techniques.