Concentrations of trans fatty acids (TFA) were determined in 6 soft-type and 6 hard-type Turkish margarines. Methyl esters of the fatty acids were analyzed on a Packard 427 model gas chromatograph equipped with a 32 mx0.3 mm capillary column containing a bonded 0.25 mu m film of BDS liquid phase. The samples in soft-type users had a total TFA concentration df 5.28%, while margarines in hard-type users had a total TFA concentration of 12.4%. Average trans monoenoic-acid concentrations in soft-and hard-type margarine users, and non-margarine users were 2.94, 11.7 and 8.68%, respectively. Average trans dienoic-acid concentrations in soft- and hard-type margarine users, and non-margarine users were 2.18, 0.50 and 1.84%, respectively. (C) 2000 Elsevier Science Ltd. All rights reserved.