About 120 species of opilionids have been described in Ecuador (7000 worldwide), The Ecuadorian Amazon is the region where the greatest number of species is concentrated. opilionids inhabit humid and shaded habitats and are generally nocturnal. these species possess glands secreting defensive secretions containing benzoquinonoids (benzoquinones and polysubstituted phenols). in this study we report the defensive compositions of neotropical opilionids inhabiting the Arajuno region, Ecuador, at the Jura Jura Kawsay Scientific Station of the Central University of Ecuador. The GC examination of the extract obtained from the defensive secretion of these Gonyleptidae (Order Laniatores, Opilinida) revealed the presence of five volatile components, three benzoquinones and two hydroquinones, being the major component 2,3-dimethyl-1,4-benzoquinone. A wide variety of benzoquinonoids have been characterized from plant and microbial sources, as well as from marine organisms.Among terrestrial invertebrates, benzoquinonoids are widely biosynthesized by arthropods including, besides millipedes, insects and opilionids. There seems little doubt that in theses invertebrates the benzoquinonoids secretions serve to repel predators and pathogenic microorganisms.