Based on the experimental results, we construct an equation of mechanical states, taking into account instantly elastic, viscoelastic, and viscoplastic momentary-elastic strain components using the constancy of the volume of the material terms of the similarity of deviators stresses and strains, as well as the introduction of parameters which are functions of the form of the stress deviator. Equation satisfactorily describes the creep strain at stationary time-dependent static and cyclic loading. An experimental study of deformation and creep in polytetrafluoroethylene (PTFE) in a linear and plane stress was performed. In the process of the experiments true stress was supported, taking into account deformations. It was build the equations of mechanical state, taking into account instantly elastic, viscoelastic, instantaneous-plastic and visco-plastic components of the total deformation. The equation used to describe PTFE strain (F-4, F-4D, F-4D0) when stationary and non-stationary mode cyclic loading in flat tension condi-tions with condition constant volume of material and similarity of deviators of stresses and strains, as well as with the introduction of the parameters that are functions of the form of the stress deviator. Relevant and difference from the works of other authors are research results creep PTFE modifications at values true stress reaches the limit. The data on the limit creep PTFE modifications included.