The objective of the experiment was to avaluate the carcass characteristics of cull cows, feedlot finished receiving diets without or with sodic monensin (200 mg/animal/day). The diet contained 12.5% of crude protein and 2.99 Mcal of digestible energy/kg of dry matter, composed of 48% of roughage (corn silage) and 52% of concentrate. Cows with monensin in the diet presented lower weight of hot (262.3 vs 289.8 kg) and cold carcass (255.4 vs 282.6 kg), hot (52.5 vs 54.9 %) and cold carcass dressing (51.1 vs 53.5%), and subcutaneous fat thickness (4.5 vs 6.6 mm) in relation to the cows without monensin. Carcasses of worse conformation were observed for the animals with monensin, reaching 8.9 points (close to regular plus) against 10.1 points (above good minus). For cows fed with monensin the sawcut showed 9,9% less absolute weight and, the amount of fat in the carcass was reduced by 20.9%. Including monensin in the diet reduced carcass weight, dressing, subcutaneous fat thickness, conformation, sawcut and fat of the carcass of cull cows. KEY WORDS: Commercial cuts, conformation, fat, subcutaneous fat thickness, weight and carcass dressing. KEY-WORDS : commercial cuts, conformation, fat, subcutaneous fat thickness, weight and carcass dressing