It is more than 40 years since the environmental contamination of polychlorinated biphenyls (PCBs) was first reported in wildlife samples. Since then, a huge number of papers on PCBs have been published, which include the biodegradation of PCBs and toxicology of PCBs. The studies on the microbial degradation of PCBs during the few decades provided significant insight into the areas of microbial ecology, biochemistry, and molecular genetics.