The present review highlights some recent advances regarding the function of polyamines in the environmental stress tolerance of plants. When exposed to adverse environmental stresses, such as salt, drought, low temperature, and ozone, the complex dynamic kinetics of polyamine biosynthesis was observed. Polyamines titers altered in different manners dependent upon several factors, such as plant species, tolerance or sensitivity to stress, and duration of stress. The exogenous addition of polyamines to stress-treated cells or tissues could lead to injury alleviation and growth promotion in most cases, although the effects varied between polyamines and among plant species. Key genes responsible for polyamine biosynthesis have been cloned from a variety of plant species, whose expressions following stress have been investigated on a molecular basis. Overexpression of the genes caused the modification of polyamine biosynthesis in the transformants coupled with enhancement of stress tolerance. All of these results seem to indicate that polyamines are an important component in a plant's response to stress and that they play a significant role in counteracting stress.