This work was carried out to evaluate the effect of soya and linseed on the chemical composition and fatty acid profi le of the Longissimus muscle of crossbred bulls fi nished in feedlot. Twenty-one crossbred bulls (1/2 Nelore vs 1/2 Simmenthal), at an average age of 18 months were used in a completely randomized design, with three treatments and seven repetitions. The dietary treatments were: control (CON), linseed and soyabean (SOYA), and soyabean and linseed added after the 60 th day of the experiment (LIN). No difference (P>0.05) was observed among the treatments on the chemical composition of the Longissimus muscle. The values of conjugated linoleic acid (18:2-c-9, t-11) were higher (P<0.05) in the LIN (0.39%) and SOYA (0.46%) treatment, as compared with the CON treatment (0.26%). n-3 PUFA values were higher (P<0.05) in the LIN treatment (1.58%) as compared with the CON treatment (0.83%).