Objective: To study the clinical features,relevant factors and measurements of impaired insight of patients with Alzheimer disease. Data sources: Using the key terms "Alzheimer disease AND insight OR awareness OR anosognosia",we searched the Medline database in English for articles on Alzheimer disease and insight published from January 1989 to December 2004 with the limits to studies on humans. Meanwhile,using the key terms"Alzheimer disease AND insight",we searched the Chinese Journals Full-Text Database in Chinese for related articles published in the same period. Study selection: All articles were selected firstly.Those related to clinical study of the impaired insight of patients with Alzheimer disease were selected.Researches on elementary studies were excluded.The full text of the rest articles was looked up, analyzed and smnmarized. Data extraction: A total of 339 English articles were selected, among which 255 were study articles and 79 met the inclusion criteria. Only one Chinese article was included because its type was abstract. Sixteen articles were included for review. Data synthesis: Insight was not "all-or-none" or "present or absent" solitarily.The mechanism of impaired insight of Alzheimer disease was unclear.At present,no recognized measurement could be used to measure the insight.The domains of insight study focused on cognition, emotion, behavior,and social living ability, etc. The influent factors of insight included the degree of dementia and dysthymia, etc. Conclusion: The impaired insight will appear in a part of patients with Alzheimer disease involving cognitive,behavioral and other domains. It correlats with dementia severity and dysthymia, etc. Still, there is no generally acknowledged measurement method of impaired insight of Alzheimer disease. The impaired insight plays an important role in the clinical studies of Alzheimer disease.