The study was carried out in 2014 - 2016 in Perespa, Poland. Soybean seeds Mavka cultivar were sown in the third decade of April. During the growing season four biostimulants: Kelpak SL (Eclonia maxima extract), Terra Sorb Complex (free amino acids), Atonik (phenolic compounds) and Tytanit (titanium) were used in four combinations each other, using lower or higher concentrations and single or double foliar spraying. All the results were compared to control (no biostimulant applied). After harvesting the plants, the antiradical activity of the seeds against ABTS •+cation radical was evaluated. Biostimulators enhance the yield quality without affecting the environment, thus they are recommended for use in sustainable agriculture. It was determined that the foliar application of Terra Sorb Complex had the most favorable influence on the studied property.