Twentyeight dens of 15 different European brown bears (Ursus arctos) were located, monitored and measured. Ten of them were used by females with cubs, 9 by females without cubs, 5 by males, and 4 by bears of unknown category. Occasionally bears used more than one den in the same winter, i.e. 4 bears used 2 to 5 dens (mean = 3). Only 2 of this den changes could be explained by human disturbance. The local abundance of natural caves is probably why the most dens (22) were built in rock cavities, 3 were ground nests under the canopy of conifers, 2 were excavated cavities under the roots of large standing trees, and 1 was in a horizontal hollow tree.