Plants are living chemical factories for enormous array of the secondary metabolites. Due to toxic and carcinogenic effects of the synthetic antioxidants, a great deal of attention has been focused in recent decades on natural antioxidants such as polyphenols derived from various natural sources. The aim of research is to study the effect of UVA on structure and medical content of yellow mustard. The results show non-enzymatic such as glutathione and phenolic contents in yellow mustard improved after exposure to UVA. Total proline, tocopherol total flavonoids in yellow mustard varied after exposure to UVA. Also internal structure as hydroxyl group of yellow mustard changed after exposure to UVA.