Introduction: Alzheimer disease (AD) is one of the best-known diseases. It is neurodegenerative disease characterized by gradual memory loss and dysfunction of behaviour. The pathogenesis of this disease is unclear. Icariin (ICA) is a flavonoid found in a Chinese medicinal herb. It is recognised for a wide range of biological and medical activities: anti-tumour and anti-inflammatory, and also has an impact on the nervous system: stimulates neuroproliferation and prevents neuron’s apoptosis. ICA may have a potential role in AD disease treatment. Objective: The purpose of this article is to review current knowledge about mechanisms and use of ICA in AD treatment. State of knowledge: AD does not present established pathomechanism, about which there are some hypotheses. Each hypothesis mentioned and checked in this review, with result that ICA may have a potential role. One well-known hypothesis is that about amylolytic which is associated with amyloid precursor protein (APP) gene mutation, which leads to amyloid beta (Aβ) protein accumulation and to occurenc of the disease. In this hypothesis, ICA may inhibit Aβ protein aggregation or alter APP expression. ICA may stifle neuronal apoptosis and promote neurogenesis and neuromodulation. According to other hypotheses, ICA could also impact on iron overload in the brain, harmful for neurons hyperhomocysteinaemia, disorder of the intracellular calcium management. Modification of theTau protein structure is another one theory of ICA action. Flavonoid from China may also have an influence on axonal transport. Conclusions: According to the literature there is no single mechanism of ICA action in slowing down AD progress. A wide range of therapeutic points is demonstrated by the broad effect of this substance. Further research is mandatory.