Abstract. The purpose of the work was to evaluate the effect of the microbiological preparation BIOR-AV on the structure, morphological characteristics and productivity of the grass mixture of Bromus inermis Leyss. and Elymus fibrosus (Schrenk) Tzvelev during the reclamation of planned clay dumps. Methods. Studies of experimental and control crops planted in 3 replicates within an area of 25 m2 were carried out during the growing seasons of 2001–2010. Projective cover and above-ground phytomass were determined on survey plots of 0.5 × 0.5 m; in each option, at least 15 plots were laid out. The dynamics of the morphological structure of vegetative and generative shoots was analyzed, and an agrochemical analysis of the substrate was carried out. Results. The positive effect of using the microbiological preparation during accelerated reclamation of dumps without applying fertile soil on the height, weight and length of leaves of vegetative and generative shoots; the number and size of structural elements of the inflorescences of the tested cereals (the length of the inflorescence, the number of branches in the inflorescence, the number of flowers, the number of spikelets, the weight of the inflorescence), and the sowing qualities of the seeds has been established. An increase in the content of the main elements of mineral nutrition in the substrate with the addition of the microbiological preparation: total nitrogen (1.6 times), available phosphorus and potassium (2 times), humus (5 times), as well as an increase in pH values from acidic to slightly acidic was revealed. The scientific novelty of the work: for the first time, in the conditions of the Middle Urals, monitoring studies of the effectiveness of the microbiological preparation on the structure, morphological parameters and productivity of a grass mixture of B. inermis and E. fibrosus were carried out on unsuitable clay substrates.