The experiment was carried out to evaluate performance, carcass characteristics, chemical composition and fatty acid composition of bulls and steers (1/2 Nellore vs 1/2 Simmental) finished in feedlot. From 8 to 20 months the animals were raised conventionally. At 20 month of age 16 bulls were randomly selected of which 8 were surgically castrated. At 32 months of age the animals were transferred into a feedlot system with individual pens of 10 m². Both groups of animals were slaughtered at 35 months of age. The bulls were heavier initially and displayed higher final weight, higher average daily gain and hot carcass weight than steers, bulls also had higher moisture content, crude protein and cholesterol and lower total fat content than steers. The ratios of PUFA to SFA and of n-6 to n-3 in bulls were higher than in steers.