The results of determining the technological quality of flax straw during processing using traditional technology are presented: yield and number of long and short fibres, total fibre yield, and complex indicators – per centimetres of flax long-stem varieties of various selections. On average, a comparative analysis of the actual values of these characteristics with the standardised values in the norms for fibre yield and quality from retted flax straw was carried out without considering the distinctive features of the varieties. It was established that compliance with the criteria per centimetres of long fibres, as the main product obtained from flax straw of different quality, ranges from 69.6% to 94.0%, and for per centimetres of short threads from 102.1% to 118.7%. As a result of studying the composition of varieties based on these characteristics to justify the choice of the most rational raw material utilisation option during processing, types with maximum and minimum values per centimetres of long fibres were identified, which are the primary criterion for the efficiency of flax processing enterprises. Based on the results of differentiated analysis by varieties with different qualities of flax straw, it is recommended to use the processing technology for both long and short fibres for such varieties as Diplomat, Alexim, Grant, Veralin, Suzanne (flax straw number 1.00), Sursky, Tost, Tverskoy, Grant, Lyra, Leader (flax straw number 1.50), Sursky, Leader, Electra, Lyra, Tverskoy, Lenok (flax straw number 2.00). For these varieties, the maximum values per centimetre of long fibres range from 98.0% to 187.9. Flax straw of sorts with the minimum value of this complex indicator is advisable to process into uniform or short wool. These include the following flax long-stem varieties: Tomsky 18, Universal, Fakel, Electra (low-quality flax straw), Tomsky 16, A-29, Praleska (medium-quality flax straw), Dashkovsky, Vasilik, Tost (high-quality flax straw). It is concluded that it is necessary to consider the distinctive features of varieties simultaneously with the quality of flax straw, which will significantly expand the possibilities for ensuring the profitable operation of enterprises.