Milipedes (Artropoda, Dipolopoda), are very ancient terrestrial invertebrates comprising around 14000 species distributed in all geographical areas of the planet. These organisms respond to any disturbance (predators) by ejecting a brown repugnatorial secretion, with purgent phenolic odor and with repellent action that can cause serious epidermal irritation to the attacker. The chemical composition of these secretions varies according to the taxonomic order. Species of the orders Julida, Spirobolida and Spirostreptida secrete p-benzoquinones, Polydesmida species discharge hydrogen cyanide and nitroalkanes, Glomerida and Polyzoniida eject alkaloids and also terpenoids such as ß-pinene and limonene. These defensive secretions constitute an ecosustainable source of biologically active secondary metabolites with potential broad-spectrum microbiocidal action. The Cuban archipelago mega-edaphofauna is characterized by endemic millipedes of the gen. Rhinocricus (R. duvernoyi and R. maximus) having the highest biomass index. These milipeds can ejaculate their secretions up to distances of 50 cm. The objective of the present communication is to report the majority composition of this secretion in individuals of the species Rhinocricus duvernoyi Karsch 1881 that inhabit the western zone of Cuba in ecogeographic formations of mogotes (karst), in La Palma (l= 83033'15" W, =22045'24 "N). The colected secretion, after a detailed chemical análisis (TLC, FTIR, CG-MS, RMN), revealed the existence of a majority componente, a new metabolite, of phenolic nature, (3,4-dimethoxyphenol) for the order Spirobolida, Family Rhinocricidae and Genus Rhinocricus, belonging to a population of the endemic millipede Rhinocricus duvernoyi Karch 1881, in the western eco-geographical zone of the Cuban archepelago La Palma (Pinar del Río). Biological activity determination is currently under development and will be published soon.