Two growth trials were carried out with a total of 112 British Friesian steers to examine the effects of offering all-concentrate diets containing different concentrations of crude protein. In Experiment 1 the steers were offered a diet containing either 17·5 % (H), 14·5 % (M) or 11·5 % (L) crude protein in the dry matter from 100 to 250 kg live weight and changed to diet M, L or one containing 9·5% crude protein in the dry matter (VL) between 250 kg and slaughter, so that the protein content of the diet offered to each steer was lowered by between 2 % and 3 % at 250 kg. In Experiment 2 the diets used were H and M between 100 and 250 kg and M and L between 250 kg and slaughter. Some steers in Experiment 2 were offered the same diet (M) throughout the experiment. Steers offered diet L between 100 and 250 kg ate less feed than steers given diet H and grew at a slower rate than steers given either diet H or M. Those steers given diet VL between 250 and 350 kg grew more slowly than those given diet M or L. For most steers a considerable saving in supplementary protein could be achieved by adopting an ML sequence rather than an HM or MM sequence when formulating dietary supplements.