The remediation of soils contaminated with various anthropogenic recalcitrant chemicals is a global problem that consumes considerable economic resources. Phytoremediation, the application of plants for the cleanup of polluted environments, uses the natural ability of plants to extract chemicals from water, soil, and air driven by photosynthesis and represents a cost-effective alternative to more established, but ecologically harmful, conventional treatment practices, such as land-filling, excavation, or incineration. Particularly, fast growing trees are promising candidates for phytoremediation due to their high biomass production, their high transpiration activity, their potential for genetic engineering, and their capability to form ectomycorrhizal associations with mutualistic fungi. Ectomycoremediation – the remediation of contaminated soils by plants and their associated ectomycorrhizal fungal communities – takes into consideration that ectomycorrhizal fungi are ubiquitous in soils and play a key role in the root rhizosphere of trees, and can substantially affect the capability of plants and their associated microbial communities to remediate contaminated sites. Ectomycorrhizal fungi are able to indirectly affect phytoremediation by increasing the plant´s ability to withstand soil phytotoxicity due to their positive effect on plant nutrition and abiotic stress resistance. Furthermore, the extraradical mycelium of the fungus acts as an extension of the root system and forms with the ectomycorrhizosphere, a niche for diverse microbial communities and their activities far beyond the root rhizosphere. Ectomycorrhizal fungi also produce a variety of degradative enzymes and can also be directly involved in the biodegradation of persistent organic pollutants, such as 2,4-D, PCBs, or TNT. This chapter highlights the synergistic interactions between plants and their fungal partners and provides an overview about our current knowledge on ectomycoremediation and its application for the remediation of contaminated sites.