With the aim of providing an up-to-date overview of LC–MS applications on the analysis of plant-derived compounds, papers published in the past few years involving qualitative and quantitative analysis of phytochemical constituents and their metabolites are summarized.After briefly describing the general characteristics of natural products analysis, the most remarkable feature of LC–MS and sample preparation techniques, the present book mainly focuses on screening and characterization of phenols (including flavonoids), alkaloids, terpenoids, steroids, coumarins, lignans, and miscellaneous compounds in respective herbs and biological samples, as well as traditional Chinese medicine (TCM) prescriptions using tandem mass spectrometer. Chemical fingerprinting analysis using LC–MS is also described. Meanwhile, instrumental peculiarities and methodological details are accentuated.