ore than 500 million tons of grain a year are produced in the world. Therefore, an increase in yield of 10-15% due to pre-sowing seed treatment with ozone will give 50 million tons of grain additionally. Search for new environmentally friendly methods of increasing the yield of grain crops and seed infection control is an urgent problem throughout the world. Gaseous ozone is best suited for this. The paper presents long-term laboratory, field and production studies of the ozone stimulating effect on germination energy, germinating capacity and yield of seeds of cereals and cotton. Combined action of ozone and fungicides of different treatment doses was studied. It has been determined that seed treatment before sowing with small doses of ozone at a concentration of about 0.5 g / m³ increases the germination capacity of cereals up to 7%, and yield - up to 15% compared to untreated seeds, while reducing the use of fungicides by 2-4 times. Pre-sowing seed treatment with an ozone-air mixture eliminates the development of surface infection by 4 to 10 times.