Assisted phytoextraction is the application of chelators into soil to enhance plant tolerance to heavy metals. During this process, water-soluble complexes of chelators and toxic elements are formed. This contributes to increased leaching of pollutants from soil into groundwater. The aim of the study was to determine the extent of leaching of mercury from soil during chemically assisted phytoextraction. The process was enhanced by use of EDTA, KI and citric acid in different concentrations. The leaching of mercury from contaminated soil was in the range 39.444.1% depending on the time and the concentration of mercury. Application of each of the chelators used during the experiment increased the leaching of mercury from soil. The highest Hg leaching was observed for the process in which EDTA was used as a soil amendment. Leaching of mercury from contaminated soil was dependent on both mercury and chelator concentration. The higher the chelator concentration in soil, the greater the mercury leaching. The results of the study showed that the lowest Hg leaching was observed in the process in which citric acid was applied to the soil. Therefore, use of this compound as a chelator during assisted phytoextraction of Hg contaminated soil should be recommended. Copyright (C) 2012 Society of Chemical Industry