In vertebrates and vertebrates, opioids are involved in the innate and specific immune responses modulation. The analogy between vertebrates and invertebrates reflect the evidence of an efficiencies et improved immune response strategies since the beginning and in course of the evolution. The regulatory functions implicated opioids are older than 500 millions years and are particularly powerful because they are conserved till human. Moreover, because of the complexity of nervous and immune systems render the studies of they fundamental mechanisms highly difficult in mammals, an alternative was to develop invertebrates models, more simples in order to better understand the process that are involved during innate immune response. These signals are at the origin of the adaptative response in vertebrates.