Different protective mechanisms are induced in plants against pollutants when they grow at extreme life conditions in contaminated areas. Ectomycorrhizal mutualistic plant-fungus symbiosis is one of these mechanisms. Some trees are better adapted to these unfavourable conditions than the others. The main reason of this phenomenon may be a success to find the proper symbiotic fungus. The result presents the process of determination of fungal species forming ectomycorrhiza with roots of a birch. The birch was distinguished by good growth and development, in spite of the fact the tree grew in the vicinity of a zinc and lead plant. The identification of mycorrhizal fungus was performed comparing a restriction fragments' pattern of the fungal ITS region with DNA isolated from fruiting bodies of Basidiomycetes fungi growing in the experimental area. The restriction analysis was preceded by PCR amplification of the ITS region.