The article is devoted to the assessment of new criteria for the selection of sainfoin biotypes in the selection process at the initial stages of organogenesis. During the laying of the nursery of the source material, the summer sowing of sainfoin was carried out. The seeds of the samples obtained by the method of positive selection from the breeding collections of scientific institutions and wild-growing populations of sainfoin were sown. New criteria for the selection of sainfoin biotypes are based on the assessment of the intensity of root system development and the calculation of the coefficient of the negative effect of drought. The selection of sainfoin families with a powerful root system of plants (a volume of more than 6.5 cm³) and the calculation of the coefficient of the negative effect of drought at a level of no higher than 0.46 allows determining families with a high adaptive potential at the initial stages of plant development. The application of the selection of breeding material according to new criteria will solve the selection problems of forming the resistance of sainfoin plants to extreme hydrothermal conditions and insufficient moisture.