Huperzine A is an alkaloid isolated from a chinese club-moss. The molecule is a potent and selective inhibitor of acetylcholinesterase. Several pharmacological and clinical studies showed that huperzine A improves the mnesic capacity and cognitive functions. Huperzine A was also found to be a neuroprotective agent. This molecule which possesses a high pharmacological potential is under clinical evaluation for the palliative treatment of Alzheimer's disease. In addition, its use in the pretreatment of poisoning by organophosphorous nerve agents could be another indication.