To date, zinc oxide varistors have been subjected to uniaxial compression to 5 kbars and hydrostatic pressures to 10 kbars. These results show a behavior between current and pressure empirically described byIL∼P7. This paper presents results of experiments in which zinc oxide varistors were subjected to hydrostatic compression up to 25 kbars. Results show a significant departure from previously reported results. The leakage current remains constant at first until a pressure of 6–7 kbars is attained. It then rises sharply and nonlinearly to a maximum value of about 55 &mgr;A at a pressure of 15 kbars, and subsequently the leakage current decreases by about two orders of magnitude as the pressure increases from 15 to 25 kbars. The limit of 25 kbars is determined by the pressure cell design and materials used. The results presented here also suggest that the varistor behavior with pressure depends on thermal annealing and strain‐induced damage processes.