This work focuses on the monitoring and evaluation of the effect of stimulating agents using the inoculation of fungi Amarita rubescens, Paxilus involutus and Laccaria proxima on the development and growth of Scots pine seedlings and the extent of mycorrhizal symbiosis. Similarly, the influence of the substrate used was monitored and evaluated. In the experiment, twelve combinations of variants, consisting of 3 variants for substrates and 4 variants for stimulatory preparations, were based. Each variant consisted of 3 recapitulations. Unpolluted peat, peat with perlite 3:1, and peat in mixture with 1: 1 pearlite formed substrate variants. Vermiculite with fungi, fungi granules and fungi-free granules formed 3 variants for stimulating preparations using mycorrhizal fungi inoculation. For comparison, 4th variant was seeded, a control sample of seedlings in which no stimulant preparations and inoculations were used. The following biometric features were observed for the variants in the number of 15 pieces: the height of the above-ground part, the weight of the above-ground dry matter, the dry weight of the root part, the total weight of the dry matter, the weight ratio of the root and above-ground part and the number of roots. The number of 7 seedlings from the variant was detected to the presence of mycorrhizal symbiosis, the presence of mycorrhizal, non- mycorrhizal,, inactive and dichotomic roots, with the inclusion of the found mycorrhiza to individual morphootypes based on the color shade. Two-factor variance analysis was used to process the obtained data, which was used for confirmation, respectively. disputes, statistically significant differences. The results of the analysis were applied in assessing the influence of substrates and stimulation preparations with inoculum on specific biometric features and mycorrhizal and its morphotypes. It has been determined whether and how seedlings and mycorrhizal symbiosis have been influenced by individual variants of substrates and stimulation preparations.