Fifty samples of human blood collected in 1992 from the general human population living in five selected areas of the Slovak Republic (the Michalovce, Velky Krtis and Nitra District, Myjava area and Bratislava) were analysed for polychlorinated biphenyls (IUPAC Nos. 28, 52, 77, 101, 105, 114, 118, 123, 126, 138(+163), 153, 156, 157, 167, 169, 180 and 189) and some organochlorine pesticides (HCB, gamma-HCH, p,p'-DDE and p,p'-DDT). PCB levels (the sum of the congeners analysed) in serum lipids averaged for all the samples analysed were 1.79 mu g.g(-1) (range: 0.53-9.20 mu g.g(-1), median: 1.33 mu g.g(-1)), HCB 5.38 mu g.g(-1) (0.16-23.20 mu g.g(-1), 4.27 mu g.g(-1)), gamma-HCH 0.012 mu g.g(-1) (<0.01-0.18 mu g.g(-1)), p,p'-DDE 6.05 mu g.g(-1) (1.30-34.80 mu g.g(-1), 4.39 mu g.g(-1)) and p,p'-DDT 0.27 mu g.g(-1) (<0.01-0.79 mu g.g(-1), 0.23 mu g.g(-1)) About three times higher levels of PCBs were found in the samples from the district where PCB formulations had been produced (the Michalovce District).