The aim of this study was to estimate live weights at 10, 40, 70, 100, 130 and 150 d, the average daily gain (ADG) for the corresponding periods and the slaughter and carcass characteristics of castrated Corriedale lambs (n=41), raised on a sustainable extensive system on natural grasslands in Rio Grande do Sul (Brazil). Weaning take place at 45 d of age. Lamb were slaughtered in November (100 d of age), December (130 d) and January (150 d). Average live weight (kg) were 6.28, 9.93, 14.39, 16.07, 18.44 and 22.59 with ADG averaging 127, 147, 105, 84 y 83 g, respectively. The slaughter season and age significantly affected the carcass components. Animals slaughtered in January, presented better conformation score and body measurements than those slaughtered in November or in December, respectively. The highest shrinkage losses were observed for 100 d lambs carcasses. Nevertheless, no significant differences between groups were observed for dressing %. Significant differences for meat color and marbling score (subjectively evaluated) were observed, but not for texture. No significant differences between groups were observed for the proportions of joints, with the exception of neck %, which was more important in older carcasses. Differences in composition were detected only for loin% in the fore limb (in favour of the 100 and 130 el groups), and for bone% in the shoulder (in favour of the 150 d group). Results obtained in this study suggest that the moment and age of slaughter affected important carcass characteristics. Additional criteria should be considered to decide the right moment to slaughter Corriedale lambs (e.g. live weight).