The aim of the study was to attempt the prognosis of seed yielding of two lucerne subspecies: Medicago sativa ssp. media and Medicago sativa ssp. sativa. The experiment was carried out on the ground of the expression evaluation of some selected traits: seed yield of 30 shoots and of 30 clusters with regard to feed productivity. The results showed that the tested lucerne subspecies did not differ considerably in relation to one year’s green matter yield; however, the seed yield differed significantly. Medicago sativa ssp. media plants gave nearly twice as high yield as Medicago sativa ssp. sativa plants. The relationship between seed and feed productivities of Medicago sativa ssp. media plants was characterized by the correlation coefficient that amounted to 0.44*. A similar correlation for Medicago sativa ssp. sativa plants was not found. The seed yield of Medicago sativa ssp. media plants could be forecast on the basis of the 30 clusters productivity (r=0.91**) and the 30 shoots productivity (r=0.92**). Applicability of the studied parameters for seed yielding ability evaluation of common alfalfa seems to be problematic due to lower values of the correlation coefficient (accordingly 0.33* and 0.5**).