Exposure to contaminants in the environment is indiscriminate and multiple species/populations of all sexes are potentially at risk. In this paper we examine the current information available on gender specific differences in invertebrates following exposure to environmental contaminants. Because of their close association with the environment and diversity of habitats, invertebrates are uniquely at risk for adverse responses to pollutants. Since 97% of all animal species are invertebrates, it would be impossible to cover each of the phyla in this review. Instead, this paper discusses major invertebrate species including insects (Periplaneta americana, Panorpa vulgaris, Lycosa hilaris, Haematobia irritans irritans (L.), and Drosophilia melanogaster), nematodes (Caenorhabditis elegans), crustaceans (Streptocephalus dichotomus, Amphiascus tenuiremis, Microarthridion littorale, Tisbe bulbisetosa, Acartia tonsa, and Palaemonetes pugio), mollusks (Pinctada fucata martensii, Ilyanassa obsoleta, Nucella lapillus, Hinia reticulata, Thais clavigera, and Mercenaria mercenaria), corals (Euphyllia ancora and Montipara capitata), and echinoderms (Asterias rubens) that have been used in studies examining the differences between males and females. Our discussion focuses on gender differences that occur in both toxicokinetic mechanisms (uptake and elimination, metabolism and physiology) and other toxicological endpoints (survival and behavior as well as morphology and development). It will become evident that the endocrine systems of invertebrates have many traits and/or pathways that are comparable to those observed in higher organisms. Yet the sensitivity of some elements of the invertebrate endocrine system, e.g., disruption of neuropeptide hormone signaling following TBT exposure, highlights the uniqueness of their systems and their potential for disruption.