Experimental evidence from animals indicates that exposure to polychlorinated biphenyls (PCBs) causes deterioration of the outer hair cells (OHCs) of the cochlea. To test this hypothesis in humans, we measured serum PCB concentrations in 574 12-year-old children residing in three districts in the Slovak Republic using high-resolution gas chromatography with microelectron capture detection. As a marker of cochlear status, we measured transient evoked (TE) and distortion product (DP) otoacoustic emissions (OAEs), and assessed the cross-sectional association between serum PCBs and OAEs. Median total PCB concentrations were 352.8, 150.5, and 134.9 ng/g lipid in Michalovce, Svidnik, and Bratislava, respectively. In multivariate regression models where otoacoustic measures were modeled as a function of log (base 10) PCB concentrations with adjustment for gender, age, and site of examination, dioxin-like PCBs, nondioxin-like PCBs and a PCB grouping targeting upregulation of hepatic uridine 5'-diphospho-glucuronosyltransferase were significantly associated with lower TEOAE powers at 1000 and 1500 Hz. At 1500 Hz, we observed a strong association with sum of PCBs and DL-PCBs, in the left ear only. The DPOAEs at 1000 Hz were associated with all four PCB groupings. The results of this study show that PCBs may affect the OHCs of the cochlea, a result consistent with findings from animal studies published to date.