In the years 1987-88 the density of the population of I. ricinus on the territory of Kraków-Częstochowa Highland including the Ojców National Park was studied. The method of collection of ticks from 100 m² fields was applied. On the spite of similar ecological conditions there was marked variation in the population density of I. ricinus. It decreased from East to West, where territories are under the strong pressure of the Upper Silesia and Olkusz industry.