In addition to participating in protein synthesis in cells and tissues, L-arginine is essential for the synthesis of urea, creatine, creatinine, nitric oxide, and agmatine and influences hormonal release and the synthesis of pyrimidine bases. This places L-arginine, its precursors and its metabolites at the center of the interaction of different metabolic pathways and interorgan communication. Thus L-arginine participates in changing the internal environment in different but simultaneous ways, ranging from disposal of protein metabolic waste, muscle metabolism, vascular regulation, immune system function, and neurotransmission, to RNA synthesis and hormone-mediated regulation of the internal milieu. In normal rats, inhibition of the nitric oxide pathway results in systemic hypertension and decreased glomerular filtration rate and effective renal plasma flow. If the inhibition of this pathway is sustained, then glomerulosclerosis and death from uremia follow. Dietary intervention with L-arginine has resulted in amelioration of a number of experimental kidney diseases, such as those caused by subtotal nephrectomy, diabetic, nephropathy, cyclosporin A administration, salt-sensitive hypertension, ureteral obstruction, puromycin amino-nucleoside nephrosis, kidney hypertrophy due to high-protein feeding, and glomerular thrombosis due to administration of lipopolysaccharide. The present review addresses the current evidence for the beneficial effects of dietary intervention with L-arginine in a number of experimental renal diseases and describes the basis for the concept of L-arginine deficiency (absolute or relative) in certain settings in which supplementation of the diet with this amino acid may be beneficial.