A method for the congener specific analysis of PCBs in human milk is described. This involves solvent extraction, acid digestion, clean-up by column chromatography and quantification by HRGC with electron capture detection and confirmation by MSD. Over 50 congeners, selected because of their reported toxicity and abundance in environmental and biological samples, are determined. Results from the analysis of UK samples of milk are presented and indicate that the mixture of congeners between different milk samples is very similar. PCB IUPAC numbers 138, 153 and 180 were the most abundant congeners, each accounting for >10% of the total PCB content of milk, while 15, 18, 28, 52, 66, 61 74, 99, 101, 105, 118, 187, 156 202 and 170 each constituted between 2 and 10%. Traces (<2%) of many of the other congeners analysed (i.e. 44, 77 110, 82 151, 119, 128, 149, 183, 188 and 201) were also found. Other congeners were either not detected (<0.5%) (eg. congeners 40, 155, 169, 185, 189 and 198), or gave erratic results (eg 30, 37, 54, 104).