The results of the study of 20 samples of cultivated flax (Linum usitatissimum L.) of the Federal Scientific Center of Bast Crops in 2021–2023 are presented. The field studies were conducted in the sub-taiga zone of the Tomsk region. Natural and climatic conditions corresponded to the requirements of fiber flax cultivation. As a result of the conducted research, valuable and flexible source material for the creation of varieties with high productivity traits has been identified. The varieties of the Pskov selection – Antey, Voskhod, Nord, Chance, Tver (Torzhok) selection – Polet, Universal, Smolensk selection – Phoenix, Impulse and standard Pamyati Krepkova – stood out in terms of total and technical length of the stems. The total stem length reached 90 cm and above, the technical stem length was more than 80 cm. The leaders in terms of fiber content in the technical part of the stems were varieties of the Tver selection (Torzhok): Tonus, Visit, Pskov varieties – Kvartet, Orion, Peresvet – 40% and higher. The highest value for the characteristic of stem slenderness (the ratio between technical length and stem thickness) was observed in the varieties Voskhod (681.0) and Peresvet (652.6). In terms of linear stem density, the varieties differed insignificantly among themselves, with most varieties having values in the range of 5.0–6.0 mg/cm. The influence of the factor " The year of inclusion in the State Register of BA of the Russian Federation" was also studied. The factor had the greatest influence on the fiber content trait. Varieties with earlier dates of inclusion in the State Register showed low fiber yield. Russian flax varieties are recognized as promising and are included in the breeding process as male and female seed parents during hybridization.