Uranium concentrations in the household water, urine, and hair of the occupationally unexposed Finnish working population were determined using inductively coupled plasma mass spectrometry (ICP-MS). The age of the randomly selected participants ranged from 18 to 66 y. The mean concentrations of uranium in water, urine, and hair were 1.25 microg L(-1), 0.016 microg L(-1), and 0.216 microg g(-1), respectively. The mean uranium concentration in hair of the Finnish working population was from 3- to 15-fold higher than the values reported in the literature, while the mean uranium concentration in urine was similar to those measured elsewhere in Europe. The observed large variation in the uranium concentrations in hair and urine can be explained by the variation in the uranium concentration in drinking water. Exceptionally high concentrations have been measured in private drilled wells in the granite areas of Southern Finland.