There is growing evidence that certain plants have evolved to contain bioactive compounds that can modulate behaviour, including cognitive performance. This chapter briey summarises the evidence pertaining to selected herbal extracts ginseng, Ginkgo biloba, Salvia, l-theanine, green tea catechins, Bacopa and guaraná. The focus is on evidence from well-controlled human trials examining the acute effects of supplementation in healthy adults. Although not discussed here, it should be noted that there is emerging evidence that some herbal extracts may also have chronic cognitive benets in various clinical and non-clinical populations.