The antioxidant effect in these bean coat extracts were further investigated by the FRAP and ABTS assays. These bean coats had a wide range of antioxidant effect , and the red sword bean coat had the highest antioxidant effect, followed by the coats of black sword bean and pinto bean, while the coat of big green soy bean had the lowest antioxidant effect. Several studies reported the antioxidant effect in selected bean coats, such as the coats of mung bean and black soy beans , while the profile of antioxidant effect in different bean coats was not intensively investigated previously. Our results indicated that pigmented bean coats had much higher antioxidant effect than most common fruits, vegetables, flowers, edible macro-fungi and cereal grains , which were evaluated by the same methods as we employed. Therefore, pigmented bean coats could be a potential source of natural antioxidants.