The geometric mean level of total DDT in serum samples (76.2 ng/mL) from 499 persons living downstream from a defunct DDT-manufacturing plant was several times the national geometric mean (15.0 ng/mL). DDE isomers, metabolites of DDT, accounted for an average of 86.7% of total DDT. Total DDT levels increased with age, even when controlled for other independent variables also significantly associated with DDT: race, sex, fish consumption, years of residence, socioeconomic status, alcohol consumption, and serum triglyceride levels. Fish consumption, the second strongest determinant of DDT level, had one third the predictive power of age. Total DDT levels were not associated with specific illness or ill health. However, total DDT levels were positively associated with levels of serum cholesterol, triglyceride, and gamma-glutamyl transpeptidase. The finding that serum DDE levels increase with age suggests that no equilibrium in body burden has been reached or that pharmacokinetics or serum/adipose partition may vary with age.