Speciation of heteroelement-containing proteins essential for human health is one of the most rapidly developing areas in bio-inorganic analytical chemistry (metallomics). We discuss recent advances in mass spectrometry (MS) techniques for detection and identification of selenium (Se)-containing proteins separated by gel electrophoresis (GE). These advances include location of Se-containing bands in 1D GE or spots in 2D GE by laser-ablation inductively coupled plasma MS (LA-ICP-MS) followed by protein identification by matrix-assisted laser-desorption/ionization MS (MALDI-MS) and nano-high-performance liquid chromatography-electrospray-tandem MS (nanoHPLC-ESI-MS2). We highlight the differences with the classical proteomics approach resulting from the presence of the Se atom. © 2007 Elsevier Ltd. All rights reserved.