The geometric mean serum level of polychlorinated biphenyls (PCBs) of 458 persons in a communitywide study was 17.2 μg/L, with 80% to 90% having levels within the range found in other community groups. As a dependent variable, PCB levels were found to be positively related to age, even when controlled for all other variables associated with PCB level: sex, local fish consumption, obesity, serum cholesterol level, and alcohol consumption. No major point source of PCB contamination was found, and fish taken in the drainage of a major population center had mean PCB levels below the current enforceable Food and Drug Administration tolerance of 5 mg/kg. As an independent variable, serum PCB levels were positively associated with γ-glutamyl transpeptidase level, serum cholesterol level, and measured blood pressure. The PCB-blood pressure association, which was independent of age, sex, body mass index, and social class, must be confirmed in other exposed populations.