The influence of mycelia growth of Trametes versicolor 2354, Flammulina velutipes 2038, Schizophyllum commune 1769 and Pleurotus ostreatus 1688 on the allelopathic properties of Corylus avellana L. and Robinia pseudoacacia L. leaves was studied using seeds of Raphanus sativus L. and Lactuca sativa L. The obtained results demonstrated that investigated plant substrates changed their allelopathic properties after mycelium growth of mushrooms. The growth of T. versicolor 2354, on both investigated substrates resulted in inhibition of lettuce and radish root length by 15-48% as compared control. The mycelia of other studied mushroom species contributed to the intensify of the growth roots of lettuce and radish on both investigated substrates in different degrees. The strongest effect was exerted by the transformed mycelium of F. velutipes 2038 leaves of C. avellana on the growth of radish seed roots. Their length increased tenfold compared to the control. The results of this study indicate the existence of a complex of factors influencing the manifestation of allelopathic activity of biotransformed in result of mushroom mycelium growth plant substrates.