In mammals, L-arginine serves as a precursor of many important physiological compounds known for several decades such as urea, creatine, ornithine, and polyamines, as well as new molecules, namely nitric oxide and agmatine, that play relevant functions in cell signaling and metabolism. Polyamines, derived metabolically from L-arginine and L-methionine, are ubiquitous cations that seem to exert an ample variety of actions in many different types of cells, both normal and neoplastic. Ornithine decarboxylase, the rate limiting enzyme in polyamine biosynthesis, has acquired an important relevance on having been postulated, in the last decade, that it may be considered as an oncoprotein. The rodent kidney plays an important function in controlling L-arginine homeostasis, since it is the major organ in the synthesis of this amino acid. On the other hand, renal polyamine metabolism presents a marked sexual dimorphism, especially ornithine decarboxylase, and although its physiological relevance is still unclear, the murine kidney can be considered as an interesting model for studying the molecular mechanisms of androgen action. In this short review we highlight different aspects of arginine and polyamine metabolism in the rodent kidney, as well as the influence of sex hormones in the regulation of the enzymes participating in both processes.