Nitrogen (N) is one of the main nutrients for plants and is a constituent of many stable compounds such as amino acids, proteins and many other molecules such as polyamines (PAs). Plant growth is mostly dependent on tissue N concentration, but frequently, N availability from the environment is scarce, and consequently, plant productivity can be compromised. Polyamines are simple molecules essential for survival. They are able to influence and regulate various developmental processes as well as plant responses to environmental stress. This review summarizes recent advances in the study of the multifaceted behaviour of PAs during the lifespan of the plants, and the study of their metabolism as a part of a network of highly interdependent pathways associated to N metabolism involving the relationship among their precursors, like glutamate, arginine and ornitine, intermediates and catabolic products like nitric oxide and γ-aminobutyric acid (GABA).