Arginine is a versatile amino acid involved in the synthesis of proteins, nitric oxide (NO), urea, polyamines, proline, glutamate, creatine, and agmatine. Key enzymes in arginine metabolism include argininosuccinate synthase, arginases, nitric oxide synthases (NOS), and arginine decarboxylase. These enzymes regulate arginine's metabolic fate in health and disease. Arginine metabolism has a rich history, with early studies identifying its role in the urea cycle and its importance in physiological processes. Recent research has expanded understanding of arginine's roles in nitric oxide production, polyamine synthesis, and other pathways. Arginine is essential for young mammals and carnivores but is conditionally essential for adults under certain conditions. The metabolism of arginine involves multiple pathways, including synthesis in the small intestine, renal conversion of citrulline to arginine, and urea cycle processes. Arginine is also involved in protein synthesis, hormone secretion, and cellular signaling. The regulation of arginine metabolism is complex, involving multiple enzymes and pathways, and is influenced by factors such as diet, hormones, and cytokines. Recent studies have highlighted the importance of arginine in various physiological processes, including vasodilation, immune responses, and neurotransmission. The metabolism of arginine is compartmentalized across different organs and subcellular compartments, and its regulation is crucial for maintaining homeostasis. The study of arginine metabolism continues to reveal new insights into its diverse roles in health and disease.Arginine is a versatile amino acid involved in the synthesis of proteins, nitric oxide (NO), urea, polyamines, proline, glutamate, creatine, and agmatine. Key enzymes in arginine metabolism include argininosuccinate synthase, arginases, nitric oxide synthases (NOS), and arginine decarboxylase. These enzymes regulate arginine's metabolic fate in health and disease. Arginine metabolism has a rich history, with early studies identifying its role in the urea cycle and its importance in physiological processes. Recent research has expanded understanding of arginine's roles in nitric oxide production, polyamine synthesis, and other pathways. Arginine is essential for young mammals and carnivores but is conditionally essential for adults under certain conditions. The metabolism of arginine involves multiple pathways, including synthesis in the small intestine, renal conversion of citrulline to arginine, and urea cycle processes. Arginine is also involved in protein synthesis, hormone secretion, and cellular signaling. The regulation of arginine metabolism is complex, involving multiple enzymes and pathways, and is influenced by factors such as diet, hormones, and cytokines. Recent studies have highlighted the importance of arginine in various physiological processes, including vasodilation, immune responses, and neurotransmission. The metabolism of arginine is compartmentalized across different organs and subcellular compartments, and its regulation is crucial for maintaining homeostasis. The study of arginine metabolism continues to reveal new insights into its diverse roles in health and disease.