The detection sensitivities and the possibilities of quantification in the ion probe analysis of microelements in tooth and bone mineralized tissue are limited partly by selective ionization yields, partly by the complicated intrinsic mass spectra of the apatite matrix. Such intrinsic spectra have been recorded for hydroxy-, fluor- and chlorapatite. The limits of analysis have been examined for most of the elements in the periodic table. With a routine SIMS technique developed for the study of mineralized tissues, the lowest concentrations for semi-quantitative measurement have been assessed to lie below 10 wt ppm for at least 20 elements and below 100 wt ppm for another 25 to 30 trace elements in apatites.