Research into the use fungistatic properties of hemp essential oil in fiber and oil flax crop protection has been conducted at the Institute of Natural Fibres and Medicinal Plants in Poznan for several years. A formulation of seed dressing was developed that does not contain any chemical synergents in its composition.During several years of experiment in developing the final formulation, seed treatments of various compositions were tested, all containing hemp essential oil. The experiment began with flax seed dressed with pure essential oil, then with essential oil diluted in different concentrations of vegetable oil, in the oil with the addition of a chemical emulsifier, in oil with organic emulsifier and oil emulgated by physical methods. Study on the effect of the formulation on the effectiveness of seed dressing b.c.a. (hemp essential oil) showed differences between the seed dressings in terms of infestation degree by the fungal disease, and obtained seed yields and quality. Laboratory tests, pot and field trials showed that the formulation at a concentration of 0.1% hemp essential oil in an organic medium and emulsified oil by physical methods proved the most effective in protecting the flax seed.