Three congeners of polychlorinated biphenyls (PCBs)--the 2, 2', 3, 4, 4', 5'-, 2, 2', 4, 4', 5, 5'-hexachloro, and 2, 2', 3, 4, 4', 5, 5'-heptachlorobiphenyls--were determined in 18 samples of butter, 44 of fish (hake and anchovy) and 24 of egg, all of which came from markets in Guipúzcoa. The total content as Araclor 1260 was also determined. Quantitation was carried out by gas chromatography in a capillary column and electron capture detector. The total content in butter ranged from 20 to 60 ng/g (fat basis), in fish from 10 to 250 ng/g (edible part), and in eggs from 1 to 10 ng/g (edible part). None of these exceeded the tolerance limits established by the Canadian Government Guideline and USFDA.