The aim of this work is to study the composition of polyphenols contained in plants of Euphorbia triodontus Prokh., growing throughout the Republic of Uzbekistan, in particular the Ferghana Valley region, using a high-performance liquid chromatograph with a diode-matrix detector (HPLC-DAD) and a tandem chromato-mass spectrometer (HPLC – Q-TOF-MS/MS).
 The roots of the plant Euphorbia triodontus Prokh., growing on the territory of Uzbekistan, collected in the period after flowering, studied the polyphenolic composition. For the first time from this type of Euphorbia, the method of stepwise hydrophobic chromatography was used to isolate polyphenolic fractions. By HPLC, as a result of semi-preparative chromatography, 6 individual compounds were isolated from the fraction eluted with a 20% methanol solution in the amount of: E-20-1 – 7 mg, E-20-2 – 22 mg, E-20-3 – 14.2 mg, E-20-4 – 41 mg, E-20-5 – 11.4 mg and E-20-6 – 32 mg. As a result of mass spectrometric analyzes, it was established that the polyphenols isolated in an individual state consist of gallic acid and glucose linked by an ester bond: O-galloyl-β-D-glucose. The structure of individual compounds was determined: E-20-1 – 1-O-meta-trigalloyl-β-D-glucopyranosyl-(4-O-β-D)-1-O-meta-trigalloyl-β-D-glucose, E-20-2 – 1-O-meta-trihalloyl-β-D-glucose, E-20-3 – 1-O-meta-tetragalloyl-β-D-glucose, E-20-4 – 1-O-meta-trigalloyl-4-O-haloyl-β-D-glucose, E-20-5 – 2,3,6-tri-O-galloyl-β-D-glucose and E-20-6 – 1,2,3,4,6-penta-O-galloyl-β-D-glucose.