Alzheimer disease (AD) is a fatal neurodegenerative disorder,and the most common cause of dementia in the elderly.Accumulated evidences in AD research suggest that alterations in the microRNA (miRNA) network could contribute to risk for the disease.As the second discovered miRNA,Let-7 has an important effect on cell proliferation,differentiation,apoptosis,immune response,tumorigenesis,metastasis,and so on.We review in this article the role of Let-7 family in the pathogenesis of AD to provide a strong basis for future research aimed at understanding the potential contribution of miRNAs to AD pathophysiology.