A relation between crystallite size and electrical properties of ZrO2 has been investigated by measurements of high-pressure electrical resistance. The resistance of nanocrystalline praseodymium-doped zirconia powders has been measured in the pressure and temperature ranges between 15 and 50 GPa, and 77 and 400 K, respectively. Around 30 - 37 GPa the resistances of all samples decrease by 3 - 4 orders of magnitude. Therefore, the anomalies in the pressure dependence of the resistance and of parameters depending on the concentration, mobility and activation energy of the charge carriers were found at ca. 40 - 45 GPa. The activation energy of the charge carriers depends on the crystallite size.