The aim of this study is to investigate the total phenolic content, concentration of flavonoids and antioxidant activity in extracts of the plant Chelidonium majus L. during different phenological stages (stage of rosette, the initial flowering stage, the stage of fully formed flowers and stage of fruits formation). Five different extracts of the whole plant, for each phase, were obtained by extraction with water, methanol, acetone, ethyl acetate and petroleum ether. The concentration of total phenolic content was determined using the Folin-Ciocalteu´s
reagent and obtained values were the highest in the rosette stage (60.96 mg GA/g). The
concentration of flavonoids was the highest in the initial stage of flowering (291.58 mg
RU/g). The antioxidant activity was determined in vitro using DPPH reagent. The highest antioxidant activity was expressed in the rosette stage (50.72 mg/ml). Based on the obtained results it can be concluded that the concentrations of secondary metabolites in Ch. majus depend on the phenological stage of the plant