A combined computer simulation and experimental study describing the viscoelastic properties of linear polyethylene is presented. For the simulation, a set of C-1000 polyethylene models were equilibrated using advanced Monte Carlo moves. Then, MD trajectories were calculated. From these simulations the entanglement molecular weight, M,, and the entanglement relaxation time, tau(e), were directly obtained. By introducing the experimental value for the plateau modulus and the simulated values for M-e and tau(e), into the reptation model, one finds that the derived curves of the relaxation shear modulus nicely coincide with the experimental ones.