There is increased interest among such diverse groups as the military, athletes, and the aged for novel plant-derived dietary supplements to enhance performance and maintain/improve health. Quercetin, a flavonoid found in fruits and vegetables, has unique biological properties that are likely to improve mental/physical performance and reduce infection risk during intense exercise. These properties include antiinflammatory, antioxidant, and psychostimulant activity, as well as the ability to stimulate mitochondrial biogenesis, and they form the basis for potential benefits to overall health and disease resistance. However, most information regarding quercetin is based upon in vitro and animal studies. Therefore, there is a pressing need for well-designed clinical trials to evaluate this novel dietary supplement further. This article will examine the recent scientific literature concerning the role of quercetin in mental and physical performance and health.