The role of free radicals in various human ailments is well established. Still, the researchers continue to emphasize the involvement of free radicals in these disorders. Antioxidants are being used as an effective tool as a defense against disorders caused by free radicals. This review presents brief detail regarding the nature, types, and sources of free radicals that are of pharmacological interest. A summary of the antioxidants, along with possible mechanisms, has also been incorporated. The role of free radicals and antioxidants in various human disease are also presented.