Mass spectrometry (MS) in combination with liquid chromatography (LC), i.e. LC-MS, is the key analytical technique on which the emerging "omics" technologies of proteomics, metabolomics and lipidomics are based. It provides both structural and quantitative data and can be used in a "global" or "targeted" manner allowing on the one hand the identification of thousands of proteins from a tissue, or on the other the detection of biologically active metabolites at levels of a few parts-per-billion. It can be expected that the continued incremental developments in LC-MS along with data-handling routines will soon bear fruit in the quest for a greater understanding of human disease, leading to new drug targets and therapies. This tutorial review on proteomics, metabolomics and lipidomics will be of interest to the biochemical, biomedical and pharmaceutical communities, as well as those working in other branches of analytical bioscience.