Relevance. Macrophytes are one of the key participants in accumulation of chemical elements in lake ecosystems, but despite this, the issue of elemental composition of macrophytes of thermokarst lakes in Western Siberia and accumulation of chemical elements relative to the sediments and pore water remains practically unexplored. The aim of the research is to describe the formation of elemental composition of macrophyte species of thermokarst lakes in the north of Western Siberia and to identify the possibility of their use in biomonitoring. The objects of research were macrophyte plants (Hippuris vulgaris L., Glyceria maxima (Hartm.) Holmb., Comarum palustre L., Ranunculus spitzbergensis Hadac, Carex aquatilis Wahlenb s. Str., Menyanthes trifoliata L.), sediments and pore waters of thermokarst lakes of the north of Western Siberia. Methods. The elemental composition of the samples was studied by inductively coupled plasma mass spectrometry (ICP/MS, Agilent Technologies, 7500 se), the concentration of anions in water samples was determined by liquid chromatography (Dionex ICS/2000), the dissolved organic carbon was defined by infrared spectroscopy TOC/VCSN, Shimadzu), the organic carbon content of the sediments was determined by infrared spectrometry (Horiba Jobin Yvon Emia/320V C/S Analyzer). Statistical processing of data was carried out using the STATISTICA 6.0 software package. Results. The coefficients of biological accumulation of chemical elements in macrophytes relative to sediments and pore water were calculated for four key thermokarst lakes. It has been shown that macronutrients (Na, Mg, Ca), some heavy metals and metalloids (Ni, Cu, Zn, Co, As, Cd), as well as B and Mo are actively accumulated in water plants of thermokarst lakes of Western Siberia. High coefficients of accumulation of heavy metals indicate a significant phytoremediation function of macrophytes in a given territory.