The main goal of the rational use of bast fiber raw materials is to develop and apply optimal methods of its processing. Work on the creation of such technologies is carried out by leading scientists of the industry in accordance with three main areas of research: the search for ways to increase the yield of long flax fiber and improve its consumer properties by using various methods of ennobling; improving the methods to unfold bundles of technical fibers and obtain elementary bast fibers (cotonized fiber); and integrating the use of waste from primary processing of bast-fiber raw materials based on existing hydrolysis and thermal decomposition technologies. However, with some exceptions, the vast majority of research is limited to laboratory experiments, largely because the bast stem is a very complex composite. This raises a number of questions for researchers. In varieties and breeding samples with high fiber quality, the total fatty acid content is higher, and the ratio of total saturated acids to unsaturated acids is lower. A method for evaluating The selection material of the same flax based on fiber quality and lodging resistance is based on determining the total content of fatty acids and total lipids and the ratio of saturated to unsaturated fatty acids in flax stalks and seeds. Subsequent comparison of the obtained indicators of the studied selection material was according to the indicators of the standard variety. Keywords: bast fibers, genesis, selection, chemical composition, physical and mechanical properties, non-cellulose components