In traditional practices of medicine, numerous plants have been used to treat cognitive disorders, including neurodegenerative diseases such as Alzheimer's disease (AD) and other memory related disorders. An ethnopharmacological approach has provided leads to identifying potential new drugs from plant sources, including those for memory disorders. There are numerous drugs available in Western medicine that have been directly isolated from plants, or are derived from templates of compounds from plant sources. For example, some alkaloids from plant sources have been investigated for their potential in AD therapy, and are now in clinical use (e.g. galantamine from Galanthus nivalis L. is used in the United Kingdom). Various other plant species have shown favourable effects in AD, or pharmacological activities indicating the potential for use in AD therapy. This article reviews some of the plants and their active constituents that have been used in traditional medicine, including Ayurvedic, Chinese, European and Japanese medicine, for their reputed cognitive-enhancing and antidementia effects. Plants and their constituents with pharmacological activities that may be relevant to the treatment of cognitive disorders, including enhancement of cholinergic function in the central nervous system, anti-cholinesterase (anti-ChE), antiinflammatory, antioxidant and oestrogenic effects, are discussed. Copyright 2003 John Wiley & Sons, Ltd.