There is a growing body of literature describing the actions of endocrine disruptors on annelids. These pollutants cause decreases in growth and reproductive output, delay sexual maturation, and inhibit the immune system in annelids. More studies are needed to determine the mechanisms that underlie these responses. Most invertebrate endocrine disruptor research focuses on steroids. In recent years many new invertebrate peptide hormones including those related to the molluscan peptide FMRFamide have been identified. Since the storage of these peptides can be inhibited by steroids during insect metamorphosis, they may be affected by endocrine disruptors. Therefore, it is worthwhile to give a brief overview of this peptide family to those studying endocrine disruption in invertebrates with the hope that they may begin to consider these peptides in their future research. In 1977 Price and Greenberg isolated FMRFamide from the cerebral ganglia of the clam, Macrocallista nimbosa. Since then researchers have used bioassays and immunoassays to identify a large number of FMRFamide-related peptides (FaRPs) from many invertebrate phyla. Even more peptides are predicted by the FaRP genes that have been sequenced. FaRPs have a variety of functions and act as neurotransmitters, neuromodulators, or neurohormones. Each function is species and tissue specific. Most FaRP receptors are linked to a second messenger system. However, at least one is a ligand gated sodium channel. On going studies are examining FaRPs from the molecular to organismal level.