DL-Leucyl-DL-phenylalanine is primarily used in the field of biochemistry and pharmaceutical research. It serves as a dipeptide model for studying enzymatic reactions, particularly those involving proteases and peptidases. This compound is also utilized in the development of peptide-based drugs, where it helps in understanding the structure-activity relationships of therapeutic peptides. Additionally, it finds application in cosmetic formulations, where it acts as a skin-conditioning agent, improving the texture and appearance of the skin. In nutritional science, it is explored for its potential role in enhancing protein synthesis and muscle recovery, making it relevant in sports nutrition and dietary supplements.