Abstract: Plastic deformation of metals and polymethylmethacrylate under the action of dynamic load is analyzed based on the relaxation model of plastic deformation. The parameters of the relaxation model of plasticity are invariant with respect to the deformation history which allows, within a unified approach, obtaining any set of deformation curves, both monotonic, with varying yield limit, and nonmonotonic, with appearing and varying yield drop, as it is observed in experiment. Increase in the yield limit and hardening effect at high-rate and static deformation of high-strength 2.3Ni–1.3Cr steel is also simulated based on the relaxation model. Exemplified by DP600 steel and nanocrystal nickel, it is shown that the relaxation model of plasticity allows predicting the smooth transition to the plastic deformation stage at slow quasi-static loading ~10 ^–3 s ^–1 and appearance of the yield drop at strain rate of 500–6000 s ^–1. In addition, it is demonstrated that the developed approach allows modeling the similar effects also for the high-rate deformation of the polymethylmethacrylate. Thus, it is demonstrated on the example of specific materials that we may use the deformation history-invariant parameters of the relaxation model of plasticity for efficient prediction of the deformation dependences of the studied materials in a wide range of strain rates 10 ^–4–10 ⁴ s ^–1.