This review covers principles and applications of ICP MS in geochemical and environmental sciences. The current popularity of ICP MS is attributed to very low detection limits for almost all elements across the Periodic Table, simple mass spectra and the ability to measure isotopic ratios. The most frequently analysed groups of elements are described in relation to the occurrence of spectral and nonspectral interferences, methods of calibration and measurement, the instrumental arrangement and also the most frequent methods of decomposition of solid samples. Modifications of the way of introducing the sample, in particular the use of electrothermal vaporisation and laser ablation, make the ICP MS a very effective instrumental method for trace analysis. However, it is necessary to take into consideration the high costs of purchase and operation of the instrument.