Different interfaces for liquid chromatography/mass spectrometry (LC/MS) such as thermospray (TSP), continuous-flow fast atom bombardment (CF-FAB), electrospray (ES) and atmospheric pressure chemical ionization (APCI) were evaluated for their potential in plant metabolite detection and identification. Natural products of various classes, mainly terpene and polyphenol aglycones and glycosides from 100-3000 u, were analysed by LC/MS and LC/MS/MS in crude plant extracts. These studies showed that TSP is suitable for the investigation of moderately polar compounds ranging up to 800 u and for glycosides having not more than two sugar units. CF-FAB permits the ionization of more polar compounds such as saponins bearing 1-8 sugar units. ES and APCI allowed the ionization of the broadest range of metabolites but showed an important selectivity for polyphenol aglycones and were sensitive to the use of modifiers (trifluoroacetic acid, ammonium acetate). The complementarity of TSP, CF-FAB, ES and APCI for crude plant extract LC/MS analysis is discussed.