Ectomycorrhizal communities associated with Pinus sylvestris L. saplings growing on abandoned post agricultural soils were studied. 1-year-old seedlings inoculated with either Suillus luteus Fr. or Thelephora terrestris (Ehrh.) Fr. had been outplanted on three sites. We investigated the long-term effect (6 and 8 years after outplanting) of inoculation on ectomycorrhizal composition and species richness. We found 17 morphotypes in total that could be identified to genus or species. In all sites the most predominant ectomycorrhizae were Suillus luteus, Thelephora terrestris, Tomentella sp., Dermocybe palustris, and Dermocybe sp. Species richness was higher in the case of inoculated seedlings grown at sites in Garwolin and Płońsk, whereas at the third site, Jabłonna, more diverse ectomycorrhizae possessed non-inoculated seedlings. The number of S. luteus mycorrhizae on seedlings inoculated with the fungus was higher than on non-inoculated ones. Dissimilar results have been found in cases of seedlings inoculated by T. terrestris. The latter possessed only 14% of the ectomycorrhizae. The results showed that persistence of inoculated fungi in roots of Scots pine is regulated by environmental conditions.