The increasing ability of mass spectrometry to address toxicological problems and the even more frequent incidence of untoward reactions to cosmetics prompted us to study preservative composition in cosmetics. Detection and confirmation of structure of unspecified preservatives (EEC legislation does not require any indication of the preservative on the label) is currently carried out by chromatographic methods that lack molecular specificity (need for reference substances), versatility and above all rapidity. We wish to describe a method for the direct and simultaneous identification of various types of antimicrobial agents in different cosmetic formulations (deodorants, shampoo, syndets, compact face powder, foot care products and mascara) by conventional electron impact mass spectrometry in combination with collisional spectroscopy (collisionally activated decomposition mass-analysed ion kinetic energy spectrometry). The method has proven to be highly satisfactory and more rapid than conventional gas chromatography/mass spectrometry (minimal or no sample work-up). In addition, it furnishes a rough indication of other basic ingredients of the cosmetic products. A simple method for quantification by single ion recording of the antimicrobial agent Triclosan (found in a large part of the cosmetics examined) is also described.