The objective of this study was to evaluate the increasing levels of crude protein of crambe meal (Crambe abyssinica) (0, 25, 50, and 75% DM) in lambs diets on the urinary excretion of urea nitrogen (UEUN). Twenty-four Santa Ines crossbred male sheep, with an average weight and age of 18 kg of body weight, and 4 mo, respectively. The experiment was conducted in a completely randomized design with 4 treatment and 6 replicates each. Animals remained 7 d for adaptation, and 3 periods of 28 d for data collection. Lambs were kept in individual pens (1.5 m x 1.0 m), equipped with trough and drinker. Animals received diets with 19% crude protein (% DM), and 65.4% total digestible nutrients (% DM), based on average daily gain of 200 g head⁻¹ with forage: concentrate ratio of 50:50. Lambs were fed ad libitum, twice a day, always at 0700 to 1500 h, allowing leftovers of approximately 20%. For determination of UEUN spot urine samples were collected by spontaneous urination on the 13th day of the second experimental period immediately at 0h, 3h, 6h and 9h after morning feeding. Data were subjected to ANOVA and regression, at 5% probability. There was no effect (P > 0.05) between diets on the UEUN, and 2.49, 2.41, 2.47 and 2.66 g day⁻¹, respectively for diets containing 0, 25, 50 and 75% of crude protein inclusion of crambe meal indicating low amount of nitrogen without being fully utilized by the animal. Therefore the inclusion of crude protein from the crambe meal for lambs feeding had a beneficial effect in relation to UEUN.