We have simulated semi crystalline polyethylene (PE) using Monte Carlo method with the Metropolis dynamics. The mechanical response is evaluated in the first steps of deformation. The simulation results are compared with the experimental curves at different conditions concerning temperature and deformation rate. The obtained results allow us to suggest that the method of MC together with the model and the dynamics employed give a satisfactory description of the mechanical properties of lineal polymers as the polyethylene. The simulations MC allows to differentiate the effect of the diverse parameters as the temperature, the test time, chain length and density which affect the mechanical behavior. The study of the non-reversible strain up to reading the material fracture is projected for future work.