A study was conducted with the objective of assessing how dietary, occupational, and residential exposures to polychlorinated biphenyls (PCBs) contribute to body burden among pregnant Mohawk women residing near three hazardous waste sites. From 1992 to 1995, 111 pregnant women were interviewed about fish consumption and other environmental risk factors and donated a 20-mL venous blood sample for serum PCB analysis. To supplement previous fish sampling, samples of residential soil, ambient air, wild duck, and local meats and vegetables were also collected and analyzed for PCBs. The results indicated a significant decline in local fish consumption from an annual mean of 31.3 meals more than 1 year prior to pregnancy to an annualized mean of 11.7 meals during pregnancy. This change was reportedly a result of the advisories issued against consumption of local fish by pregnant and nursing women of childbearing age. The geometric mean concentration of total PCBs in the serum was 1.2 ppb, a level that is similar to that in other studies of women with no unusual exposures to PCBs. However, multiple regression analysis revealed that serum levels of total PCBs and three individual congeners were associated with local fish consumption. The PCB levels in soil, air, and local foodstuffs other than fish generally were not elevated, except for those obtained in close proximity to one of the hazardous waste sites, and no association was found between serum PCB levels and exposure through these media or through occupation.