Among the factors that influence the yield of sunflower, the density of plant standing in specific soil-climatic conditions is important. One of the measures to provide plants with the necessary minerals is the pre-treatment of sunflower seeds with bio-fertilizers in order to improve nutrition, increase productivity and protect plants from phytopathogenic fungi. The aim of the research was to determine the effect of plant density and seed treatment with biological fertilizers on the production of sunflower hybrids. The experiments were conducted in 2012-2014 at the Research Field of the Institute of Oilseeds. Objects of research were hybrids of sunflower of domestic breeding: Institute of oilseeds – Polyet, Region; Institute of Plant Breeding them V.Ya. Yurieva – Site, Borey; Selection-Genetic Institute – Odesskiy 249, Syuzhet. The sowing was carried out at a depth of seeding of 6-7 cm with a width of 70 cm spacing. Three densities of plant standing were studied: 40, 60, 80 thousand per hectare. Variants of application of biological fertilizer polymicobacterin: 1. Control (seed treatment with water); 2. Sowing treatment of seeds (12 ml/kg). According to the results of three years of research, biometric indices and performance indicators of sunflower hybrids: Polyet, Region, Site, Borey, Odesskiy 249, Syuzhet were changed under the influence of plant density and application of biological fertilizer polymicobacterium for processing seeds. Greater plant height of sunflower hybrids: Polyet – 136.1-136.5 cm, Region – 133.8-134.5 cm, Site 138.3-139.4 cm, Borey – 138.1-139.3 cm, Odesskiy 249 – 135.6-137.1 cm, Syuzhet – 138.6-139.3 cm marked by the density of plant standing 60 thousand/ha. In the crops with a plant density of 40 and 80 thousand/ha, this figure decreased. Indicators of the area of the leaf surface on 1 plant, depending on the option of pre-treatment of seeds, decreased with the thickening of crops from 40 to 80 thousand/ha: from 52.7-53.8 to 23.4-23.6 dm2 in the hybrid Polyet; from 53.0-54.3 to 23.6-23.9 dm2 in the hybrid Region; from 50.2-50.4 to 22.7-23.2 dm2 in the hybrid Site; from 48.2-49.1 to 23.4-23.5 dm2 in the Borey hybrid; from 52.2-52.3 to 23.8-23.9 dm2 in the hybrid Odesskiy 249; from 51.6-52.7 to 23.1-23.5 dm2 in the hybrid Syuzhet. The area of the leaf surface on one hectare was greater than the density of planting sunflower 60 thousand/ha and was: in the hybrid Polyet 20.6-20.8 thousand m2; in the hybrid Region 20.8-21.2 thousand m2; in the hybrid Site 20.4-20.8 thousand m2; in the hybrid Borey 19.6-20.0 thousand m2; in the hybrid of Odesskiy 249 21.1-21.6 thousand m2; in the hybrid Syuzhet 20.0-20.4 thousand m2. Indicators of mass of 1000 seeds of sunflower, depending on the application of polymyxactarin, decreased with the thickening of crops, respectively: from 46.4-46.6 to 41.0-41.1 g in the hybrid Polyet; from 47.8-48.0 to 42.2-42.4 g in hybrids Region; from 45.4-45.7 to 40.6-40.9 g in the hybrid Website; from 44.0-44.2 to 39.3-39.5 g in the Borey hybrid; from 50.1-50.3 to 44.1-44.5 g in the hybrid Odesskiy 249 and 45.0-45.2 to 41.4-41.6 g in the hybrid Syuzhet. The largest indices of the mass of 1000 seeds of all hybrids studied were indicated in variants with seed dressing and plant density of 40 thousand/ha. Increase from the use of the drug was 0.1-0.4 g. The analysis of the obtained data showed that the highest yield of hybrids studied in the experiment was obtained for the density of 60 thousand/ha in variants with pre-seed treatment of seeds and was: Polyet 2.00 t/ha, Region 1.99 t/ha, Site 2.09 t/ha, Borey 1.86 t/ha, Odesskiy 249 1.91 t/ha, Syuzhet 2.00 t/ha. Reducing the density of plants up to 40 or up to 80 thousand hectares led to a decrease in yield by 0.02-0.14 t/ha. The most productive among hybrids was the Site. The increase in yield from the use of biological fertilizers, depending on the density of plant standing, was: in the hybrid Polyet 0.02-0.03 t/ha, in the hybrid Region 0.04-0.07 t/ha, in the hybrid Site 0.03-0.08 t/ha, in the hybrid Borey 0.04-0.08 t/ha, in the hybrid Odesskiy 249 0.06-0.07 t/ha, in the hybrid Syuzhet 0.05-0.06 t/ha. At the same time, the largest increase in the yield of six hybrids was obtained for the density of plants standing at 60 thousand/ha. There was no significant effect of biological fertilizer on the fat content of the seeds. Taking into account the level of yield, the highest yield of oil: hybrid Polyet – 859, hybrid Region – 858, hybrid Site – 877, hybrid Borey – 773, Hybrid Odesskiy 249 – 790, hybrid Syuzhet – 834 kg/ha has provided sunflower cultivation with a density of plant standing of 60 thousand/ha and using polymeric bacterium for seed treatment before sowing.