The emerging field of metallomics refers to the entirety of research activities aimed at the understanding of the molecular mechanisms of metal-dependent life processes. This critical review discusses the concept of metallomics with a focus on analytical techniques and methods for the probing of interactions between metal ions and the organism's genome and the derived -omes: proteome and metabolome. Particular attention is paid to the in vivo screening for the native metal-protein and metal-metabolite complexes by hyphenated techniques that combine a high-resolution separation technique (gel electrophoresis, chromatography or capillary electrophoresis) with sensitive elemental (inductively coupled plasma, ICP) or molecular (electrospray or MALDI) mass spectrometric detection. The contribution of bioinformatics to the prediction of metal-binding sequences in proteins and the role of molecular biology approaches for the detection of metal-dependent genes, proteins and metabolites are highlighted (115 references).