In order to assess the extent of polychlorinated biphenyl (PCB) exposure and potential health effects, a clinical-epidemiologic survey was initiated among 205 workers at a capacitor manufacturing plant. The geometric mean serum PCB level for workers was 18.2 ppb (SD 2.88), with a range of 0 to 424 ppb. Multiple regression analysis found duration of employment, cumulative occupational exposure, cumulative fish consumption, and cholesterol level to be significant predictors of log serum PCB levels. Of these predictors, duration of employment and cumulative occupational exposure were the strongest contributors to the regression model, indicating the dual importance of opportunity for dermal contact and respiratory exposure level in contributing to workers' serum PCB levels.