The present review focuses on the emerging evidence regarding the potential of polyphenols to act as acetylcholinesterase inhibitors. This enzyme plays a fundamental role in the body and its inhibition may play a role in the control of various pathologies, including Myasthenia gravis, Glaucoma and Alzheimer's disease. Polyphenols are present throughout the human diet and their potential effects in ameliorating the quality of life and to prevent human ageing are the subject of numerous and varied research. In this review we outline the potential influence of polyphenols on acetylcholinesterase with a particular view to describing their actions in the brain. Following an introduction to the biochemical actions of the enzyme and its active site, we will present an overview of the reported actions of polyphenols, in particular flavonoids and tannins, to act as acetylcholinesterase inhibitors. We will also highlight structure-activity relationships and how metabolism of polyphenols during absorption affects their function. Finally, we discuss the evidence for some foods to possess acetylcholinesterase inhibitor activity.