The aim of the study was to conduct a comparative biochemical study of plant raw materials of different varieties of Trifolium pratense L. and identification of the most valuable for cultivation in the Udmurt Republic. The objects of the study were 6 varieties of Trifolium pratense L. of Russian and foreign selection. On average, over 2 (2018-2019) years of research, the varieties of Trifolium pratense L. Dymkovsky and Kudesnik were distinguished by the collection of dry aboveground biomass 5.60 and 5.99 t/ha. The plant raw materials of the studied varieties of Trifolium pratense L. contained 3.5-4.1% crude fat, 1.87-2.26% nitrogen, 0.58-0.64% phosphorus, 2.57-3.10% potassium and 1.00-1.17% calcium, which allows us to consider it as a promising source of these elements. The highest content of nitrogen and calcium was observed in the Diplo and Lestris varieties, potassium - in the Dymkovsky and Kudesnik varieties, and phosphorus-in the Rannij 2 variety. The content of the flavonoids sum in terms of rutin in the studied plant samples of Trifolium pratense L. was at the level of 1.3-2.4%, the highest - in the variety of foreign selection Lestris.