Twenty-eight Rambouillet cross lambs (27.85 ± 2.91 kg) were used in a 74-d feedlot experiment to evaluate the influence of zilpaterol hydrochloride (Zilmax, Merck Animal Health) and enriched-Cr yeast (BioChrome, Alltech) supplementation on carcass characteristics and meat composition of feedlot lambs. Lambs were weighed and individually allotted. They were randomly assigned to 4 treatments as follows: 1) A 85% concentrate corn-SBM diet, contained 15.5% CP and 1.87 Mcal NEm/kg, (Control); 2) Control with 0.2 mg of zilpaterol hydrochloride/ kg BW during last 28 d in the feedlot (ZH); 3) Control with 0.3 mg of Cr/kg DM (YCr); and 4) Control with ZH and YCr (ZHCr). Lambs were harvested, hot carcass weight measured and carcass dressing obtained. After 24 h chilling, longissmus dorsi muscle was cross sectioned at the 12th rib, and then back fat thickness and rib eye area were recorded. Longissimus dorsi samples were taken and meat chemical composition determined. Results were analyzed as a completely randomized design in a 2 × 2 factorial arrangement. Hot carcass weight tended to be greater (P = 0.10) in ZH (20.9 vs. 20.3 kg). Hot carcass dressing (46 ± 0.35%) was not different across treatments (P > 0.20). Back fat thickness was not affected by ZH (P > 0.20), but Cr tended (P = 0.10) to increase back fat thickness (2.02 vs.1.67 mm). Rib eye area (25 ± 0.68) was similar across treatments (P > 0.20). Meat dry matter, ash, and CP content were not altered by treatments (P > 0.10). ZH decreased (P = 0.03) fat content (28.3 vs. 39.14 g/kg). Shear force of the meat from lambs fed ZH treatments was greater (P < 0.01) than in meat lambs not fed ZH (5.8 vs. 2.8 kg/cm²). Cooking losses were similar across treatments (P > 0.10). In conclusion, zilpaterol hydrochloride supplementation contributed to greater carcass weight and reduced fat content of meat, but shear force was greater. Yeast-Cr tended to increase back fat thickness without benefit in other carcass or meat characteristics.