Experimental studies on the use of microbiological preparations in the cultivation of oil flax in the system of organic farming are relevant, as they address the needs for sustainable development. The work aims to summarize experimental studies on the effect of microbiological preparations on the elements of the crop structure and yield of oil flax in the crop rotation of organic farming in the southern Steppe of Ukraine. Experimental studies were conducted in 2023-2024 at the Institute of Climate-Smart Agriculture of the National Academy of Agrarian Sciences of Ukraine according to the Methodology for State Variety Testing of Crops (2000) and the Methodology for Field Experimentation (Irrigated Agriculture) (2014) and recommendations for organic farming. It was found that the treatment of oil flax seeds and plants led to an increase in the number of bolls by 7.1-19.6% and 5.2-9.0%, the number of seeds by 1.2-11.5% and 1.8-16.2%, the weight of 1000 seeds by 0.2-6.7% and 0.7-2.7%, and the weight of seeds per plant by 4-12% and 9.5-19.0%, compared to the control. The use of microbiological preparations contributed to the reliable preservation of seed yields in ‘Orfei’ and ‘Zhyvynka’ varieties within 0.04-0.16 t/ha and 0.05-0.19 t/ha, respectively. In most cases, two-time application of ”Ekofosforyn” (Az. chroococcum, Az. vinelandii, Agr. radiobacter and B. Megaterium) together with ”Biospektr BT” (Pseudomonas with a titer of at least 5.0-109 CFU/cm3) and ”Metarizin BT” (Metarhizium with a titer of at least 2.0. 109 CFU/cm3) also led to an increase in the number of capsules and seeds per plant in both varieties by 12.5-13.4% and 6.6-14.0%, and the weight of 1000 seeds and seed weight per plant by 4.9-1.3% and 10.7-16.0%. The treatment with such a biological complex additionally preserved the yield at the level of 0.16 t/ha in the ‘Orfei’ variety and 0.19 t/ha in the ‘Zhyvynka’ variety.