The pseudocereals such as buckwheat, quinoa, amaranth have attracted interest in recent years. One of the reasons for this renewed interest is their excellent nutrient profile. In addition to being one of the important energy sources due to their starch content, these pseudocereals provide good quality protein, dietary fibre and lipids rich in unsaturated fats. The aim of our work was to study antioxidant activity in 4 chosen cultivars of common buckwheat during vegetation period. Four cultivars were analysed: Spacinska, Bambi, Jana C1, Aiva. Samples of plant material were obtained from Plant Producion Research Centre in Piestany. Antioxidant activity (AOA) of stem, leaves, flowers and seeds of buckwheat was assessed with using of DPPH radical (2.2 - diphenyl-1-picrylhydrazyl) at wavelength 515.6 nm. The antioxidant activity of buckwheat was evaluated in growth phases I. (formations of buds), in phase II. (at the beginning of flowering), in phase III. (full flowering), in phase IV. (full ripeness). The antioxidant activity in stems of all tested cultivars of common buckwheat was in range from 49.109 % (Spacinska, phase I.) to 73.705 % (Spacinska, phase IV.). The antioxidant activity in leaves of all tested varieties of common buckwheat was in range from 77.937 % (Bambi, phase IV.) to 99.655 % (Bambi, phase II.). The antioxidant activity in flowers of all tested varieties of common buckwheat was in range from 88.75 % (Bambi, phase III.) to 92.665 % (Spacinska, phase I.). The antioxidant activity in seeds of all tested cultivars of common buckwheat was in range from 39.787 % (Spacinska, phase III.) to 88.241 % (Bambi, phase III.). From the standpoint of antioxidant activity in individual plant parts the cultivars Spacinska, Bambi were the most suitable ones for food productions.