Data from three experiments involving 552 steers that were program fed supplemental protein to more closely meet their requirement were analyzed to determine if changing source or quantity of supplemental protein affected the performance of finishing steers when implanted. Comparisons were made during the beginning portions of the experiments when the cattle were implanted with estradiol benzoate and the last portion of the experiments when they were reimplanted with estradiol benzoate and trenbolone acetate. The diets were also compared during the weigh period immediately after the steers were reimplanted and again during the second weigh period after reimplanting. During the first implant period steers fed soybean meal gained faster and were more efficient than those fed urea, indicating supplementing a corn-based diet with urea did not provide adequate metabolizable protein for optimum performance. However during the second period performance was similar for steers fed soybean meal continuously, changed from soybean meal to urea or fed urea continuously. Steers fed the three diets performed similarly during the initial 21-d period or the second 21-d period following reimplanting with estradiol benzoate and trenbolone acetate. The results of these studies show that the quantity of supplemental protein fed to cattle can be significantly reduced by strategically changing from SBMbased to urea-based supplements and even a low protein urea-supplemented diet without affecting response to anabolic implants.