The internal burden of arsenic among 5- to 14-year-old eastern German children in the heavily polluted areas of Hettstedt, a region of smelting and copper mining, and Bitterfeld, a center of chemical production and coal mining, was compared with that in a control area (Zerbst) by means of urinary arsenic concentrations in 1992-94. The unadjusted geometric mean among the 950 children was significantly higher in Hettstedt (5.1 micrograms/l; 95% C.I. 4.8-5.5) but not in Bitterfeld (4.3 micrograms/l; 95% C.I. 3.7-4.9) compared with the control area (4.0 micrograms/l; 95% C.I. 3.5-4.5). This difference persisted after adjustment for relevant confounders. Despite these regional differences, recent fish consumption was as strongly associated with urinary arsenic levels (42% increase, 95% C.I. 18-71%). Additionally, although the geometric mean among the children in Hettstedt (4.8 micrograms As/g creatinine; 95% C.I. 4.5-5.1) was higher than that found in an environmental survey of eastern German children (3.60 micrograms As/g creatinine; 95% C.I. 3.06-4.24), it was similar to that found among western German children (4.59 micrograms As/g creatinine; 95% C.I. 4.20-5.02). This suggests that the arsenic contamination in Hettstedt is not substantially increasing the internal burden of arsenic among children above that found in other German children.