Field experiment demonstrated the benefit resulting from biological soil management including the use of N<sub>2</sub>-fixing and growth promoting bacteria A. brasilense B-4485 for long-fibred flax. Seed inoculation by A. brasilense B-4485 was equivalent to the introduction of 15 kg/ha of N that provided the possibility of partial flax N requirement supply. Treatment A. brasilense + N<sub>15</sub>P<sub>60</sub>K<sub>90</sub> is considered to be the most profitable management in regard to flax yield and its quality, and is comparable to N<sub>30</sub>P<sub>60</sub>K<sub>90</sub> treatment. Biological management allows preventing high concentrations of N in soil, excludes lodging and negative effects on flax yield and its quality. Implementation of biological management for flax nutrition may be profitable for both ecology and economy of long-fibered flax growing.