BACKGROUND trans fatty acids are associated to several health disorders, as ischemic heart disease or diabetes mellitus. OBJECTIVE to assess the content of trans fatty acids in products in Spain, and the percentage of trans fatty acids respecting total fatty acids. METHODS 443 food products were acquired in Spain, and they were classified into groups. The content in fatty acids was analyzed using gas chromatography. Estimates of central tendency and variability of the content of trans fatty acids in each food group were computed (in g of trans fatty acids/100 g of product). The percentage of trans fatty acids respecting total fatty acids was calculated in each group. RESULTS 443 products were grouped into 42 groups. Median of trans fatty acids was less than 0.55 g / 100 g of product in all groups except one. 83 % of groups had less than 2 % of trans fatty acids, and 71 % of groups had less than 1 %. CONCLUSIONS the content of trans fatty acids in Spain is low, and it currently doesn't play a public health problem.