The purpose of this study was to evaluate the economic viability of producing crossbred lambs in feedlots, and to determine which slaughter weight is more profitable. Fifty-three male and female animals were used, from three different genetic groups: Santa Inês (SI), Ile de France x Santa Inês (ISI) and Texel x Santa Inês (TSI). The animals were slaughtered at different body weights (BW) (30, 35, 40 and 45 Kg). Only variable costs were analyzed, as other costs were presumed to be fixed. The BW operational cost per kg was R$ 4.01, R$ 3.58 and R$ 3.38 for SI, ISI and TSI, respectively. The animals slaughtered with 45 kg BW cost R$ 3.51 per kg of BW produced, which was significantly lower than other groups. With estimated revenue of R$ 3.50 per kg of BW, sheep production in the Federal District (DF) is not profitable. The use of management practices to increase the number of twin births may increase the gross profit margin of the activity. Payment for carcass weight and meat quality as well as the improvement of productivity indices and better food conversion obtained by animal breeding programs are urgently needed to guarantee sheep production profitability.