Arginine is one of the amino acids with multiple metabolic pathways. Apart from its role in the composition of proteins, it is the biosynthetic precursor of nitric oxide, creatine, agmatine, proline, homoarginine and polyamines. In chapter One of this book, the reasons for and the possible advantages and disadvantages of nutritional arginine supplementation are critically discussed in the light of established biochemical results. Chapter Two summarises the position and importance of the L-arginine in nitric oxide homeostasis, disbalance of which can be one of the causes of many acute and chronic diseases. Chapter Three provides a brief overview of L-arginine and cardiometabolic health. Chapter Four discusses the use of novel synthetic biodegradable arginine-rich implantable biomaterials and devices for human body repair and reconstruction. Chapter Five reviews beneficial effects of L-arginine supplementation in controlling blood pressure. Chapter Six reviews the recent information about the advantages of using L-Arginine as a dietary supplement to improve reproductive function in certain female domestic animals, such as the ewe, sow, and mare, as well as in female rats and humans.