Due to their reduced elytra many adults of free living rove beetle taxa (Coleoptera: Staphylinidae) bear exocrine defensive glands where an astonishing variety of defensive compounds, antimicrobics, fungicides, adhesives or spreading active compounds are produced. Chemically these exocrines cover hydrocarbons, aliphatic alcohols, aldehydes, ketones, acids, esters, sprioacetales, iridoids, aromatics, quinones or various nitrogen-containing compounds. Factors such as presence, position, structure and variation of these exocrine glands are used more and more in order to establish a natural system of Staphylinidae. This paper surveys the chemical defensive systems of staphylinid beetles and considers the biological significance and multifunctional role of these exocrines. Within the omaliine group, Oxytelinae/Pseudopsinae, Aleocharinae, Paederinae, Staphylininae/Xantholininae, Steninae and Silphidae where a common homologous gland system is present in each case, character patterns and evolutionary trends, especially with respect to secretion chemistry are presented. In the subfamily Oxytelinae these glandular and micromolecular patterns are used especially in order to construct a phylogeny for this subfamily which is based on phylogenetic systematics. It was shown that identification of character stage transformations of these micromolecules in advanced and primitive species is necessary for estimating apomorphic and plesiomorphic character states. Optimizing of a defensive secretion may on the one hand be achieved by gradual intervention of new secretion types (from one precursor) with increasing topical irritancy from primitive towards advanced taxa. A further improvement of the secretion may be achieved by changing and adjusting secretion formulation in order to optimize these mixtures by synergisms from primitive towards advanced species. Finally the necessity of biogenetic data is stressed in order to discuss the gradual sequence of evolution of gland constituents.