L-Phenylalanine hydrazide is primarily used in biochemical research as a reagent for the synthesis of various compounds. It serves as a building block in the preparation of peptides and other biologically active molecules. In pharmaceutical studies, it is utilized to develop potential drug candidates, particularly in the field of enzyme inhibitors and receptor modulators. Additionally, it finds application in the study of metabolic pathways and the investigation of amino acid derivatives. Its hydrazide group makes it a valuable intermediate in organic synthesis, enabling the formation of hydrazones and other derivatives for further chemical transformations.