In Thailand, DDT was banned for agriculture use in 1983 and for malaria vector control in 1999. However, contamination by DDT and its primary metabolite, p,p'-DDE remains serious environmental and human health concerns. The main focus of this study were i) to investigate serum concentrations of p,p'-DDE and p,p'-DDT as exposure biomarkers for potential adverse health effect in adult Thai residents and ii) to compare the associations of BMI, thyroid hormones, cholesterol, triglycerides and fasting blood sugar levels in human serum with the concentrations of these pesticides. In a total of 1,137 participants were measured blood serum for analyses of p,p'-DDE and p,p'-DDT. The geometric mean concentration (95% confidence interval) for serum total p,p'-DDE concentration was 1,539 (1,242-1,837) ng/g lipid and 1,547 (1,293-1,806) ng/g lipid in adult males and females, respectively. Furthermore, the total amount of serum p,p'-DDE concentration significantly correlated with plasma glucose levels. Neither p,p'-DDE nor p,p'-DDT was significantly associated with serum thyroid hormones levels. Additionally, the high p,p'-DDE/DDT ratio indicates that the exposure is due past rather than recent use of DDT.