The suitability of inductively coupled plasma mass spectrometry (ICP-MS) for the determination of trace amounts of inorganic elements in clinical samples has been investigated. Protein solutions, which were known to be free from biohazards, were obtained in sufficient amounts to allow the preparation of three pools of material of differing trace metal content. Freeze-dried portions were distributed to four different laboratories with established expertise in trace element analysis. The elements Mg, Al, Cr, Mn, Fe, Ni, Cu, Zn and Se as determined by ICP-MS showed reasonable agreement with the values obtained by inductively coupled plasma atomic emission spectrometry (ICP-AES), simultaneous multi-element atomic absorption continuum source (SIMAAC) spectrometry and by established flame and graphite furnace atomic absorption spectrometry (FAAS and GFAAS) procedures. A commercial source of freeze-dried urine with assigned values for a range of trace elements was analysed by ICP-MS. Acceptable results were obtained for elements with mass numbers greater than 81 (e.g., Pb, Cd, Hg and Tl). However, with the exception of Co, results obtained for the first row transition elements, as well as for As and Se, were severely degraded by polyatomic interferences. Acid digests of dried bovine liver (NBS SRM 1577) were also analysed by ICP-MS and acceptable agreement with the certified values found for Mn, Fe, Cu, Co, Rb, Zn, Sr and Mo. Modification of the sample preparation procedure by precipitation of chloride prior to analysis by ICP-MS has been found to offer advantages for some elements.