Lead concentrations were measured in the deciduous teeth (incisors) of 302 children living in a lead-smelter area in the FRG (Stolberg, Rheinland) and of 86 children living in a nonpolluted rural area (Gummersbach, Bergisches Land). Blood lead levels were determined in 83 of the children living in the lead-smelter area. On average, tooth lead levels of children living in the smelter area (mean: 6.0 microgram/g; range: 1.49-38.5 microgram/g) were significantly higher than those of children living in the rural area (mean: 3.9 microgram/g; range: 1.6-9.4 microgram/g). Blood lead levels were 6.8-33.8 microgram/100 ml (mean: 14.3 microgram/100 ml). Children of lead-workers had on average higher tooth lead and blood lead levels than children of people who were not lead-workers. Tooth lead levels increased with increasing duration of residence in the lead-smelter area and with the degree of local environmental pollution by lead, as indicated by the lead content of the atmospheric dust fall-out around the children's homes. The correlation coefficient of tooth lead vs blood lead was 0.47. The intra-individual variability of tooth lead levels was low (r = 0.86), and tooth lead levels of brothers and sisters were similar (r = 0.75), suggesting that tooth lead may be used as a representative and reliable indicator of long-term lead exposure.