The use of agroindustrial byproducts in cattle diets, such as castor-bean (Ricinus communis L.) meal, is a more sustainable practice because it does not compete with human food and reduces the volume of organic waste deposited in the environment. The aim of this study was to examine the effect of replacing soybean {Glycine max (L.) Merr.) meal with castor-bean meal on the intake, digestibility, feeding behavior and performance of crossbred steers supplemented while on Urochloa brizantha (Hochst. ex A. Rich.) R.D. Webster 'Marandu' pasture. The experiment was laid out in a randomized complete design with 40 animals, which started the experiment weighing 227.1 kg, at 10 mo of age, and were divided into four treatment groups. Castor-bean meal was added to replace soybean meal at the levels of 0, 90, 180, and 280 g kg.sup.1 in the supplement, which was supplied at the rate of 0.4% of body weight. Total DM, pasture DM and neutral detergent fiber intakes did not change (P > 0.05) with the castor-bean levels added to the supplement. Ether extract intake and digestibility decreased linearly (P < 0.05). The animals showed no differences (P > 0.05) in production performance (average daily gain), which averaged 0.65 kg d.sup.1 Grazing, idle, and rumination times were not influenced (P > 0.05) by the treatments. Castor-bean meal can be included up to 280 g kg.sup.1 in the total diet without changing the performance of crossbred steers finished on tropical pasture. Key words: Beef cattle, biodiesel by-product, steers performance, Ricinus communis, Urochloa brizantha.