ICP-MS techniques based on isotope dilution analysis can be regarded as an emerging tool in quantitative protein analysis. Well-known concepts, for example species-specific and unspecific isotope dilution analysis, which promoted accurate and precise quantification in elemental speciation studies, have nowadays been transferred to the analysis of large biomolecules, e.g. proteins. Besides detection of heteroatom-containing proteins, the artificial introduction of metal-containing labels has attracted much attention and, as a consequence, ICP-MS-based isotope dilution techniques can serve as a valuable quantification tool. In particular, because isotope dilution ICP-MS techniques can enable absolute protein quantification, they can be regarded as an attractive technique in current and prospective proteomics. In this review, recent developments and applications will be highlighted and critically assessed.