Using the urinary biomarkers 1-hydroxypyrene-glucuronide (1-OHPG), 2-naphthol, and malondialdehyde (MDA), we evaluated seasonal and regional variations in polycyclic aromatic hydrocarbon (PAH) exposure and oxidative stress among Korean adults and children. In total, 322 children (175 male and 147 female) and 332 adults (47 male and 285 female) were recruited in two regions of Korea, one representing a metropolitan area (Seoul/Incheon) and the other an industrial (Pohang) area, from winter 2002 to spring 2003. The subjects voluntarily gathered their first morning urine void, which was immediately transported to our laboratory and stored at -20 °C. Urinary 1-OHPG was measured by synchronous fluorescence spectroscopy, 2-naphthol by HPLC, and urinary MDA by HPLC with a UV detector. The median urinary 1-OHPG concentration tended to be higher in the industrial region than in the metropolitan region (0.92 vs. 0.77 ng/mL; p=0.03), and higher in winter than in spring (0.95 vs. 0.73 ng/mL; p<0.001). The median 2-naphthol concentration was also higher in the industrial region than in the metropolitan region (21.0 vs. 12.3 ng/mL; p<0.0001), but was higher in spring than in winter (19.7 vs. 10.3 ng/mL; p<0.0001). The median MDA concentration was significantly higher in winter than in spring (2.19 vs. 1.03 μmol/L; p<0.0001), whereas regional variation in MDA was observed only in female adults (p=0.02). In winter, the level of 1-OHPG was higher in children exposed to environmental tobacco smoke than in unexposed children (0.94 vs. 0.86 ng/mL; p=0.02). Our results indicate that both region and season can significantly influence the levels of PAH exposure and oxidative stress biomarkers.