Medicinal herbs and herbal preparations have been used for many centuries against different acute and chronic diseases, and various studies have shown that herbal extracts can be a good source of antioxidants that prevent the emergence of diseases and aging. The aim of this research was to determine and compare the antioxidant activity of plant infusions prepared from roots and leaves of selected medicinal herbs and it has been shown that among the different species there are obvious differences in the range of results. The DPPH radical reduction method by spectroscopic electron spin resonance (ESR) was a method used to provide a precise and successful measure of the concentration of radicals in the sample. The obtained results were compared with the available data in the literature and results from a similar published researches. The leaf extract of the mountain germander has shown the strongest antioxidant characteristics by bringing the ESR signal to the area below the detection limit of the instrument itself. The weakest antioxidant effect had the root extract of dandelion, since it inhibited the smallest number of DPPH radicals. The antioxidant activity of the root and leaf of the same herbivore, nettle, was studied and it was proved that different parts of the plant, due to their different polyphenolic and chemical-mineral compositions, have different antioxidant characteristics. The size of the particles affects the extraction of biologically active substances from medicinal plants because the extract of crushed particles contains more antioxidant compounds and with that the higher inhibitory ability to remove DPPH radicals