Cognitive impairment is one of the main health problems commonly seen in people suffering from neurodegenerative disorders like Alzheimer's disease(AD), Parkinson's disease(PD), Schizophrenia etc. To treat such conditions of cognitive impairment, numerous plants have been documented in various traditional system of medicine like Ayurvedic, Chinese, European and Japanese medicine. An ethno pharmacological approach may help us to identify potential new drugs from plant sources, including those for memory disorders. There are numerous drugs available in allopathic medicine that have been directly isolated from plants, or are derived from number of compounds extracted from plant source. This article reviews some of the plants and their active constituents that have been shown to produce positive results in various cognitive impairment models.