Forty years ago manufacturers commonly used polychlorinated biphenyls (PCBs) in a wide variety of products. In the late 1970s, following research demonstrating neurotoxicity in animals, even at low levels, PCBs were banned internationally. Today PCBs are widespread environmental contaminants and may be isolated from breast milk of women worldwide. This article provides an overview of the current research on the relationship between PCBs in breast milk and their effects on breastfed children with regard to neurological effects, growth and maturity, potential mitigating effects of breastfeeding, and immunologic effects. The vast majority of results from this body of research indicate that despite higher PCB loads, breastfed children continue to fare better than their formula-fed peers. At this point, there is no evidence of a threshold among the general population beyond which the risks of breastfeeding outweigh the benefits, nor is there any evidence demonstrating a clinically significant negative effect of postnatal exposure to PCBs via breast milk. To date the majority of studies conclude that despite substantially higher PCB loads among breastfed infants, breastfeeding is still preferable to formula feeding.