The crustaceans are ecologically and economically important organisms. They constitute one of the dominant invertebrate groups on earth, particularly within the aquatic realm. Crustaceans include some of the preferred scientific model organism, profitable aquaculture specimen, but also invasive nuisance species threatening native animal communities throughout the world. Chemoreception is the most important sensory modality of crustaceans, acquiring important information about their environment and picking up the chemical signals that mediate communication with conspecifics. Significant advances have been made in our understanding of crustacean chemical communication during the past decade. This includes knowledge about the identity, production, transfer, reception and behavioral function of chemical signals in selected crustacean groups. While it is well known that chemical communication is an integral part of the behavioral ecology of most living organisms, the intricate ways in which organisms allocate chemicals in communication remains enigmatic. How does the environment influence the evolution of chemical communication? What are the environmental cues that induce production or release of chemicals? How do individuals economize production and utilization of chemicals? What is the importance of molecule specificity or mix of a molecule cocktail in chemical communication? What is the role of chemical cues in multimodal communication? How does the ontogenetic stage, the sex or the physiological status of an individual affect its reaction to chemical cues? Many of these questions still represent important challenges to biologists.