The aim of the paper is the reveal effect of the quartz particle size on the mechanical properties of the electroporcelain subjected to cyclic test. This paper describes the influence of quartz on the mechanical properties of electroporcelain. The amount of quartz was controlled during sample preparation. Eight groups of samples were manufactured by extrusion with the addition of 0, 1, 2, and 4 wt.% of quartz and two different quartz grain sizes of 200 μm and 64 μm. Samples were fired at the temperature of 1320 °C, which is a common temperature for this type of ceramics. Once the nominal value of mechanical strength for each group was determined, the samples were cyclically tested using 50% of the nominal mechanical strength. The samples were tested by a 3-point bending machine for obtaining mechanical strength. The obtained values exhibited, that with an increasing amount of quartz, the mechanical strength decreased. On the other hand, the amount of quartz did not have a significant impact on cyclic tests. The influence of the amount of quartz on the value of mechanical strength after 100 and 500 cycles was negligible. However, the quartz grain size had a significant effect on the mechanical strength. The smaller grain size of impurities led to a lower degradation effect.