Polychlorobiphenyls ( (\mathrm{PCBs}) ) have been produced since 1930 and exploited for a variety of purposes, including use in transformers, capacitors, paints, pesticides, and many other highly developed industrial activities. The high chemical and physical stability and the lipophilic characteristics of these compounds are responsible for their long-term persistence in the environment and for their ability to bioaccumulate. These reasons, along with the discovery of the widespread environmental occurrence of these pollutants and the possible connection of their presence to carcinogenesis, has led in the past few years to PCBs being included in the list of priority pollutants. thus making their monitoring in the environment and studies of their toxic effects on living organisms of prime importance. This paper describes analytical methodologies, interference elimination procedures, and quantitation criteria for PCB analysis in several different environmental matrices. The individual determination of non-ortho chlorinated congeners, whose toxicity factors are comparable with those of tetrachlorodibenzo-p-dioxins, and the application of supercritical fluid extraction and chromatography for their separation, and Fourier-transform infrared spectrometry for their identification are also discussed. 1995 Academic Press, Inc