From an evolutionary point of view, one of the most important forms of memory is taste-recognition memory. When an animal eats, food-related cues are associated with the consequences of its ingestion. So, if a new taste is associated with malaise, animals will reject it on the next presentation, developing a long-lasting taste aversion. Conversely, when taste is not accompanied by digestive malaise, it becomes recognized as a safe signal, and the animal increases its consumption. In this review, the putative molecular signals and biochemical events that mediate the formation of safe and aversive taste-recognition memory traces are discussed.