Abstract: Phytotoxicity of aluminum ion (Al3+) is a serious problem limiting crop production in acidic soils. Organic acids with Al_chelating ability play an important role in the detoxification of Al both externally and internally. Aluminum is detoxified externally by the secretion of organic acids such as citric, oxalic, and /or malic acid from the roots. The secretion of organic acids is highly specific to Al and the site of secretion is localized to the root apex. The kinds of organic acids secreted as well as secretion patterns differ among plant species. Internal detoxification of Al_accumulating plants is achieved by the formation of Al_organic acid complex. For instance, the complex of Al_citric（1:1)in hydrangea and Al_oxalate(1:3) in buckwheat has been identified. In the paper the role of organic acid in detoxification of aluminum in higher plants and its mechanisms are reviewed.