Amaranth is an ancient plant belonging to the Amaranthaceae family, which is believed to have originated in Central and South America. The high nutritional quality of the amaranth seed protein is one of the main factors that has attracted the attention of the researchers. However, till date, the protein profile of the leaves of the most researched varieties has not been well studied. Moreover, the nutritional profile of Amaranthus dubius remains unknown. Therefore, it would be interesting to study it. Protein from A. dubius leaves has a high nutritional value due to its balanced amino acid composition. The concentrations of albumins, globulins, prolamins and glutelins are 73.42, 6.60, 6.47 and 6.11%, respectively. It was found that the best agent for extraction of globulins was Na2HPO4 and for glutelins, it was NaOH. The highest amino acid content was found in the albumins fraction and the lowest one in the glutelins fraction. The chemical score of the essential amino acids from proteins of the leaves of A. dubius flour was 92.83%; the flour has only one limiting essential amino acid: Leucine (Leu). The leaves of A. dubius can be used as complement dietary for rice, wheat and corn proteins.