Crambe meal, which is a co-product of biodiesel production, is a potential substitute for conventional protein sources in ruminant diets. The objective of this study was to evaluate the effect of the substitution of crude protein of the concentrate by crude protein of crambe meal with increasing levels (0, 25, 50, and 75%) on nitrogen balance and blood plasma urea nitrogen concentration in sheep. Four male sheep, rumen fistulated, were placed in metabolic crates and distributed in a 4 x 4 Latin square design. Diets were composed of 50% roughage (corn silage) and 50% concentrate. The results were submitted to analysis of variance and regression at 5% of significance. No effect was observed on nitrogen balance (P > 0.05). There was a linear decreasing effect (P < 0.05) for plasma urea nitrogen. According to the results obtained in the present study, it can be concluded that crambe meal can be used as an alternative protein feeding and it can replace up to 75% of the concentrate crude protein, since it assures consumption and use of nitrogen similar to conventional feeding.