The interdisciplinary field of marine invertebrate chemical ecology is relatively young, and particularly so in polar marine environments. In this review we present evidence that the incidence of chemical defense in antarctic benthic marine invertebrate phyla is widespread. Mechanisms of chemical defense have been detected in antarctic representatives of the Porifera, Cnidaria, Brachiopoda, Tunicata, Nemertea, Mollusca and Echinodermata. This argues against earlier biogeographic theories that predicted a low incidence of chemical defense in polar waters where levels of fish prédation are low. Selection for chemical defense in benthic sessile and sluggish marine invertebrates is likely a response to an environmentally stable community shown to be structured primarily by biotic factors such as prédation and competition. Holoplankton and the eggs, embryos and larvae of both benthic and planktonic antarctic macroinvertebrates may also employ chemical defense to offset mortality during characteristically slow development and long life span where susceptibility to prédation is seemingly high. While most research to date has focused on the role of secondary metabolites in mediating pré dation, it is likely that bioactive compounds in antarctic marine invertebrates also serve roles as antifoulants and allelochemics. The diversity of bioactive metabolites detected to date in antarctic marine invertebrates sets the stage both for continuing and for broadening efforts to evaluate their functional and ecological significance.