In this review a method of characterizing gum rubbers according to their viscoelastic properties is discussed. Measurements of small shear deformation, with linear behavior and large elongational deformation with nonlinear behavior are recommended as minimum but adequate means. The method of data analysis is given for relating viscoelastic properties to the gum rubber processability. The method also differentiates rubber with respect to the types of gel and to the relative length of branches. Examples of polyethyl acrylate rubbers (ACM) and cis-1,4-polybutadiences (BR) are presented.