The effect of sire breed (Corriedale: C, Texel: TX, Île de France: IF and Milchschaf: MI), the sire used (number of rams: 13) and the lamb sex (ram: r, wether: w, cryptorchid: c and female: f) on growth traits on two target class of lambs (light: 20-24 kg; heavy: > 30 kg), and carcass characteristics of 127 male lambs slaughtered at a fixed date with 147 ± 9.5 of age and 32.4 ± 5.3 kg of live weight were studied. Growth rate was affected by crossbreeding (p ≤ 0.0001). The best results were obtained with IF and in heavy lambs (166 g/day, 180 g/day, 199 g/day, 182 g/day of growth rate on lambs C, TX, IF y MI, respectively). Under these conditions the fat score of lambs before slaughtering was also improved (3.6, 3.6, 3.4 y 3.4, IF, TX, MI y C, respectively). Crossbreedings affected all characteristics of carcass analyzed (p ≤ 0.05), excepting weight of leg, Psoas muscles and bone (p > 0.05). Crossbred animals showed carcass weight 11‑25% higher than pure C lambs, with higher weights corresponding to IF sired lambs (p ≤ 0.01). Male lambs (rl and cl) showed a greater growth rate versus fl and wl, particularly when the type of obtained product corresponded to heavy lambs. As a counterpart, fl showed a better body condition for light and heavy lambs. Sex affected only GR (coral tissue thickness at the 12 rib, 110 mm from the midline) and weight of Longissimus dorsi muscle (p < 0.05) of car­cass characteristics. Differences (p < 0.10) between the rams utilized were also found, but only for growth characteristics.