Forty crossbred (Santa Ines × Dorper) ram lambs (21.7 ± 2.7 kg BW, 90 d old) were used to evaluate the effects of high concentrations of crude glycerin on some blood parameters of energy metabolism. Lambs were assigned to a complete randomized block design (initial BW) and fed four isonitrogenous (18.4% CP) and isocaloric (2.7 Kcal ME/kg) experimental diets containing corn silage (40%), and concentrate (60%) composed of soybean hulls, soybean meal, mineral premix, and crude glycerin replacing 0 (G0), 10 (G10), 20 (G20), or 30% (G30) corn cracked grain, on a DM basis. Crude glycerin totally replaced corn grain in G30 and it was composed of 83% glycerol, 95% DM, 6% salt, and less than 0.01% methanol. The feedlot period lasted 66 d (21 d adaptation [three step-up diets] and 45 d finishing period). Animals were fed twice daily (0700 and 1900 h). Blood samples were collected from the jugular by venipuncture on the d 0 and d 45 of finishing period (day effect), before morning feeding and 4 h after feeding (prandial effect). Serum total cholesterol (TC), serum triglycerides (TG), blood glucose (BG), serum HDL-cholesterol (HDL), serum LDL-cholesterol (LDL), and serum VLDL-cholesterol (VLDL) were evaluated. Data were analyzed using a linear mixed model with Kenward-Rogers adjustment for calculation of degrees of freedom. Whenever the F-test was significant, contrast analyses were performed and differences of least squares means were determined using the pairwise Tukey–Kramer multiple test. Crude glycerin did not change BG concentrations, but a day effect was observed (P < 0.001) for this variable. A linear decrease in TC was observed with increasing concentrations of crude glycerin in the diets (P = 0.02). A prandial effect was observed for TG (P = 0.001) and for VLDL (P < 0.0001), while HDL concentrations linearly decreased (P < 0.001), and showed a day effect (P < 0.001) and a prandial effect (P = 0.02). The concentration of LDL linearly decreased with crude glycerin inclusion, and showed a significant day effect (P < 0.001). The average values (mg/dL) observed for treatments G0, G10, G20, and G30 were, respectively: TC = 41.0, 41.2, 36.4, 36.1; TG = 12.5, 13.2, 12.1, 15.3; BG = 83.6, 85.7, 82.1, 87.2; HDL = 13.3, 12.7, 11.4, 10.7; LDL = 25.2, 22.9, 23.8, 22.3; VLDL = 2.5, 2.6, 2.4, 3.1. Feeding crossbred finishing lambs up to 30% crude glycerin can decrease the concentration of some blood parameters of energy metabolism, such as total cholesterol, HDL and LDL.