Free radicals (super oxide, hydroxyl radicals and nitric oxide) and other reactive species (hydrogen peroxide, hypochloric acid and proxynitrite) produced due to environmental chemicals, endogenous chemicals, especially stress hormones and during aerobic metabolism. These oxidative species react with cell components such as lipids, proteins, mitochondria and DNA, can cause oxidative stress and contribute to various diseases in humans including schizophrenia, Alzheimer’s atherosclerosis, arthritis, ischemia, neuronal degradation, gastritis, aging, liver diseases, cancer and AIDS. Antioxidants, both exogenous and endogenous helps to neutralise the effect of free radicals by different mechanism of action include: prevention of the free radical formation by scavenging free radical scavengers, preventing the radical chain reaction of oxidation, inhibiting the oxidation process and increase shelf life by retarding the process of lipid per-oxidation. Antioxidants may be synthetic and natural. Butylated hydroxyanisol (BHA), butylated hydroxytoluene (BHT), tertbutylhydroquinone (TBHQ), 2-tert-butyl-4-methylphenol (TBMP) and propyl gallate (PG) are synthetic antioxidants used in food industry. But some synthetic antioxidants have been reported dangerous for human health. Superoxide dismutase (SOD), Catalase (CAT) and Glutathion peroxidase (GTx) are well known enzyme found in plasma act as endogenous antioxidants by transforming reactive oxygen and reactive nitrogen species into the stable compounds. There are various phytochemicals isolated from plants such as vitamins A, C and E, polyphenols, flavonoids, tannins, lignans, phytoestrogens, saponin, betacarotene, anthocyanins and lycopene possesses antioxidant property with no side effect. Therefore, it is worthwhile to isolate phyto-constituents from these reported antioxidant plants deserve further evaluation in clinical studies for the benefit of mankind.