Seventeen wood-decaying mushroom species (Coriolus versicolor, Flammulina velutipes, Ganoderma sp., Hypholoma fasciculare, H. sublateritium, Kuhneromyces mutabilis, Lentinula edodes, Lentinus tigrinus, Pholiota alnicola, Ph. aurivella, Ph. destruens, Pleurotus cornucopiae, Pl. ostreatus, Polyporus subarcularius, Po. squamosus, Po. varius and Schizophyllum commune) were paired with three Trichoderma species (T. harzianum, T. pseudokoningii, and T. viride) and Clonostachys rosea in dual-culture experiments on an agar-based medium. Xylotrophic mushrooms and mycoparasitic fungi in general showed similar competitive ability; deadlock, or mutual inhibition after mycelial contact, was observed in 45.6% of pairings, while stable inhibition at a distance occurred in 4.4% of pairings. Replacement, or overgrowth of xylotrophic mushroom by a mycoparasitic fungus was observed in 29.4% of pairings; the opposite, overgrowth of the xylotrophic mushroom on the mycoparasitic fungus in 20.6%. of pairings. Of the xylotrophic mushrooms, Pl. ostreatus, Ganoderma sp., F. velutipes and H. fasciculare, showed the highest competitive ability against mycoparasitic fungi. Of the mycoparasitic fungi, T. harzianum showed the strongest competitive activity against xylotrophic mushrooms.