Abstract: Over recent years a tremendous interest has been shown in the yielding and plastic deformation of polymers. The studies of this area in the last two decades or so are reviewed. The main discussions are focused on three parts: the first is the yielding criteria of isotropic and anisotropic polymers, the second is concerned with the theories of thermally activated yielding and plastic deformation, and the third is an outline of stress-strain behaviour and related constitutive relations. While reviewing variou...