Antioxidants are substances which help to defend the body against cell damage caused by various free radicals. Free radicals are unstable oxygen molecules containing unpaired electrons. Reactive oxygen species (ROS), such as superoxide anion, hydroxyl radical, and hydrogen peroxide, have a causal relationship with oxidative stress. Role of free radicals has been implicated in several diseases such as liver cirrhosis, atherosclerosis, Cancer, aging, arthritis, diabetes etc. The quantities of the Butea monosperma aqueous and benzene extracts needed for in vitro inhibition of hydroxyl radicals and lipid peroxidation were relatively similar to the known antioxidant ascorbic acid.