Antioxidants are the defense system of the body against the damage of reactive oxygen species which physiological processes in the body 1, 2. There are various sources of these antioxidants like endogenous antioxidants present in the body and exogenous in food source. Some biological properties such as anti-carcinogenicity, anti-mutagenicity, anti-allergenicity and antiaging activity have been reported for natural and synthetic antioxidants 3. Among the sources of natural antioxidants, the most important are thosse coming from routinely consuming vegetables and fruits 4, 5, however, antioxidants from other plants and agriculture waste should not be ignored. Natural oxidants are widely distributed in food and medicinal plants. The present paper provides comprehensive basic information about antioxidants, how do antioxidants work, types of antioxidants and their main resources from food and their main resources from and medicinal plants.