Based on a literature review of the occurrence of polychlorinated biphenyl (PCB) congeners in commercial formulations, environmental and biological samples and human tissues, and a consideration of the relative toxicity and persistence of the congeners, suggestions are made as to the most relevant components to be quantified by a selective congener analytical approach to human foodstuffs and tissues. These criteria suggest congener numbers 28, 74, 77, 99, 105, 118, 126, 128, 138, 153, 156, 169, 170, 179 and 180 will give a measure of > 70% of the total PCB tissue burden in a sample and be of greatest toxicological significance. Additionally, congeners 8, 37, 44, 49, 52, 60, 66, 70, 82, 87, 101, 114, 158, 166, 183, 187 and 189 are considered because of their reported occurrence or toxicity.