The electrical breakdown of low density polyethylene films 100 &mgr;m thick was investigated experimentally and theoretically under high hydrostatic pressure (1 to 500 bar) at temperatures of 20, 70, and 90 °C. The theoretical analysis was based on combining the two basic mechanisms of thermal and electronic breakdowns by introducing a new parameter, pressure. This model mainly takes into account the transient current using the hopping transport phenomenon and local electric field distortion due to the presence of space charges in the material. The results of simulation show good agreement with experiments compared to our previous works on the modeling of electrical breakdown in which the effect of space charges was neglected. ©1997 American Institute of Physics.