[en] Radiation counting of nuclear decay events is the most commonly used method of measuring radionuclide concentrations. However, some radionuclides, such as transuranics: ²³⁵U, ²³⁶U, ²⁴⁰Pu, ²⁴¹Pu, ²⁴²Pu, and the fission products: ⁹⁹Tc and ¹³⁵Cs can be analyzed by mass spectrometry with greater sensitivity, ease, and/or accuracy. Mass spectrometry also offers an independent means of measuring radionuclide concentrations which can be valuable as a comparison with radiation counting. Current capabilities of mass spectrometry for analysis of selected environmental radionuclides as well as projected developments for the near future are summarized. Comparisons of cost, sensitivity, and accuracy (with a particular emphasis on sensitivity) are made for those radionuclides of most interest to environmental studies and for those most likely to lend themselves to mass spectrometric analysis. In some cases where there are presently no mass spectrometric methods which are competitive with radiation counting, limiting factors are defined, and the possibility of future developments is discussed