[en] This report comprises working papers presented at an Advisory Group Meeting organized by the International Atomic Energy Agency. Fourteen contributions from seven countries describe measurement systems, and their applications, for the in vivo study of human body composition, mainly with respect to the elements calcium, nitrogen, sodium, chlorine, phosphorus, cadmium and lead. The techniques used include neutron activation analysis, X-ray fluorescence analysis, computerized axial tomography, nuclear resonance scattering and photon absorptiometry. Also included is a collection of ''system descriptions'' containing information on equipment developed for such measurements at seventeen centres in eight countries (institute address and name of persons to contact for more information, overall system performance, irradiation and country device, estimated cost)