Cadmium concentrations were determined in the hair of 226 school children in an industrial and in a rural area of Tarragona Province (NE Spain). The influence of sex, age, hair color, smoking habits of the household members, and parents' occupation on the children's hair cadmium levels was also evaluated. Children living in the industrial area had much more cadmium in their hair than those living in the rural area (median: 0.327 vs 0.002; arithmetic mean: 0.401 vs 0.119 micrograms/g). Girls had more cadmium in their hair than boys, and cadmium levels decreased with the age independently of the sex. Smoking habits and parents' occupation also influenced the hair cadmium content in the children examined. In contrast, hair color has no influence on hair cadmium values.