Polyamines (PAs) are polycationic aliphatic amines ubiquitously present in all living organisms. In plants, polyamines play vital role in myriad of physiological functions including, growth, development and biotic and abiotic stress responses. The most common polyamines present in the plants are putrescine, spermidine and spermine. Postharvest application of polyamines has been found effective in delaying ripening, senescence and extending shelf life of fruits and vegetables. Polyamine reduces the biosynthesis of ethylene by sharing the common precursor S-adenosyl methionine, required for production of ethylene. In addition, PAs also plays important role in maintaining firmness, reducing respiration rate, color changes, mechanical damage, chilling injury, etc. during postharvest storage of fresh fruits and vegetables. In this chapter, the influence of postharvest exogenous polyamines on fresh fruits and vegetables, safety and acceptance issues, and future line of work is discussed.