The purpose of this study was to evaluate the profitability and economic viability of the lambs termination in confinement compared four diets with different proportions of grass hay Brachiaria brizantha cv. BRS Piatã and fresh disabled soybean. In the survey was used information zootechnical and economic confinement of 20 lambs and, based on this information a simulation was done by designing an enclosure with accommodation for 50 animals per cycle termination. The fixed cost were analyzed, like as the variable, effective operating cost, total operating cost and total cost, its components and their participation in the total cost. In all diets the acquisition cost in finishing lambs had the highest share in total cost, followed by food, labor, taxes and variable rates, and interest on working capital. The finishing period influenced the number of lots and the number of animals terminated during the year and the production of carcass. It was found that the increase in use of soy concentrates and disabled increase production efficiency and improve economic performance in finishing lambs in confinement. However the diets evaluated had negative economic results, therefore, are not economically viable.