The effect of flax seed dressing with biopreparations, chitosan, and its derivatives on fungal communities in soil was evaluated. Biopreparation organisms consisted of: Pseudomonas aureofaciens, P. fluorescens, Pythium oligandrum, a mixture of photosynthetic and Lactobacillus bacteria, and unidentified yeasts and fungi. Chitosan and its derivative active ingredients were used: chitosan microcrystalline, chitosan acetate, and chitosan oligomers. Untreated flax seeds and seeds dressed with Zaprawa Oxafun T 75 DS fungicide containing carboxin and thiram active ingredients were used for controls. In general, Pythium oligandrum caused a greater decrease in soil fungal colony-forming units (cfu) than the Zaprawa Oxafun T 75 DS fungicide and all other preparations tested. Pseudomonas aureofaciens and P. fluorescens generally produced similar decreases in soil fungal cfu compared to fungicide controls. Chitosan and its derivatives almost always caused a decrease in fungal cfu, but these decreases were less pronounced than that in fungicide controls.