Alfalfa samples (sowing alfalfa – represented by cv. Legend, and hybrid alfalfa – represented by cv. Radius) were subjected to stimulation 1, 3 and 5 times with divergent beam of He-Ne laser. Alfalfa was harvested in the 3-cut system in years of full land use. Plant samples were used to determine the content of dry matter, total protein, specific protein, crude fibre, phosphorus, potassium, calcium, magnesium, copper, manganese, zinc, boron and molybdenum. Pre-sowing stimulation of seeds with laser light, at doses R6x5 and R6x3, caused a significant increase in the content of specific protein, phosphorus and molybdenum, while decreasing the content of crude fibre in the dry matter of the plants.