Polychlorinated biphenyls (PCB) are the most wide spread environmental pollutants and a prominent contaminant known to have toxic effects on humans and animals. They are well known as mutagens and carcinogens and affect almost all systems of the body. Due to their resistance to biodegradation and lipophilic properties, PCB bioaccumulate in tissues of human through regular food consumption. PCB are also known to cross the placenta and to be secreted into the motherÂs milk, thus predisposing the infant to adverse health effects. Further, a higher incidence of bacterial infections was reported for breast-fed infants. While, data regarding the PCB-induced immuno toxic effects in humans are scarce, however data derived fromexperimental animals, include nonhuman primates, indicated that the immune system is a potential target for the immunotoxic effects of PCB. Additionally, PCB have the potential of partially antagonizing the effects of other structurally related compounds including the highly toxic dioxins, which are also present in small amounts in the environment. Thus, to fully evaluate the magnitude of the immunotoxic risk of PCB to humans, consideration should be given to investigate the interactive effects of PCB. In this context the present article focuses to reveal the biological effects of PCB and their bioremediation by bacteria.