The fatty acid composition of dietary fats and oils from 14 European countries was analyzed with particular emphasis on isomeric trans fatty acids. The proportion of trans fatty acids in typical soft margarines and low-fat spreads ranged between 0.1 and 17% of total fatty acids and that of cis-unsaturated fatty acids between 55 and 81%. Hard household margarines and industrial fats for cooking and baking (shortenings) had slightly higher proportions of trans fatty acids and highest amounts, up to 50%, were found in fats for deep frying. Vegetable oils contained only small amounts of trans fatty acids, usually less than 1%. Isomers of C18:1 comprised up to 94% of the trans fatty acids in hardened vegetable oils and 52-68% in butter, whereas hardened fish oils showed a more even distribution of trans monoenoic fatty acids between C16:1 and C22:1, and C18:1 isomers contributed by 28 -42% to total trans fatty acids. Fat spreads with very low content (ฯฝ1%) of trans fatty acids were found in all but one of the countries, and a general tendency to products lower in trans fatty acids was observed in most countries for soft margarines and low-fat spreads but not for industrial fats and fat products for cooking and frying. The fatty acid composition of the spreads indicated that both C12-16 saturated fatty acids and cis-unsaturated fatty acids had been used to replace trans fatty acids in the low-trans fatty acid products in the different countries but the use of increased amounts of stearic acid was very limited.