The glycerine metabolization have influence on lipogenesis and could potentially improve the meat quality. The aim of this study was to determine the effect of dietary glycerine level (as an energy source) on the Longissimus muscle (LM) fatty acids in bulls finished in feedlot. Forty Purunã bulls (¼ Aberdeen Angus + ¼ Caracu + ¼ Charolais + ¼ Canchim) were distributed in a completely randomised design into 4 treatments during 229-d: G00: without glycerine; G06: 6% glycerine; G12: 12% glycerine; G18: 18% glycerine on a DM. The bulls were slaughtered (472 ± 57.3 kg) at commercial slaughterhouse. LM samples were taken between the 12th and 13th ribs after chilling (24-h at 4 ºC) of the carcass. LM saturated FA concentration was reduced in bulls receiving glycerine in their diets. LM mono-unsaturated and poly-unsaturated FA increased in bulls fed diets with glycerine. The n-6 and n-3 PUFA concentrations increased in bulls fed diets with glycerine. The PUFA:SFA ratio was lower with the diet containing no glycerine. The PUFA n-6:PUFA n-3 ratio was not significantly different between treatments. Glycerine is an interesting source of dietary energy, which can successfully substitute corn in beef finishing diets and which provides a meat healthier fatty acids profile.