Forty-eight steers were used to study the influence of feeding soybean oil (SO) on the conjugated linoleic acid (CLA) content of beef. Steers were fed either a control diet containing 954 g/kg of dry matter (DM) corn-based concentrate (CTL) or a control diet supplemented with SO at 20 (SO2) or 40 g/kg (SO4) of diet DM for 105 days. Adipose tissue samples were collected from the M. longissimus dorsi (LD) and from the M. semitendinosus (ST) on days 0 and 63 of the experiment. Adipose and muscle tissue samples were collected from the LD and ST immediately after slaughter. Feeding 40 g/kg of DM as SO increased the proportions of trans-C18:1 in beef lipid as compared to CTL and SO2 treatments. The C18:2 cis-9, trans-11 isomer of CLA as a proportion of total fat was not different in adipose and muscle across treatments. Supplementing SO increased C18:2 trans-10, cis-12 CLA in adipose tissue of the LD. Supplementing high-grain finishing diets with SO is not an effective strategy to enhance the C18:2 cis-9, trans-11 isomer of CLA in beef. Keywords: Beef; conjugated linoleic acid; soybean oil; fat; fatty acid