Objective To investigate trans-fatty acids(TFAs) contents and composition in some commercially available foods of Shanghai,and provide reference for risk assessment and food selection.Methods During January~June 2011,9 categories and totally 106 kinds of representative sold foods from Shanghai supermarket,bakery and fast food restaurant were assayed by silver ions solid phase extraction-Gas chromatography(Ag+-SPE/GC),including vegetable oil,milk and milk products,snacks,convenience foods,handy foods,beverages,ethnic foods and cakes,condiments and poultry meat and products.Results Trans-oleic acids(t C18∶1) were main kinds of TFAs isomer in samples selected,and trans-polyunsaturated fatty acids only accounts for a small part.TFAs were found in 105 kinds of all the 106 products with black coffee an exception,in which chocolate pie was the highest content of TFAs(1 711.58 mg/100 g).11t C18∶1 isomer was relative high within ruminant animal foods and foods containing milk and milk products(accounting for 53.9%-100.0% of total TFAs).9t C18∶1 isomer was relative high in snacks containing hydrogenated oil(accounting for 14.3%-87.7%).TFAs contents of pork and beef processed were reduced to different extents.Conclusion According to the test,most commercially available foods in markets contain the TFAs,among whose ingredients and processing procedures diversify the total TFAs contents and the composition of isomers greatly.Some kinds of prepackaged snacks and foods from western cake stores contain more TFAs.