© 2015, Chartered Inst. of Building Services Engineers. All rights reserved.The objective of this study was to investigate the effect of different fattening systems on the slaughter and carcass traits of male Hemsin lambs. Hemsin lambs were divided into three groups; extensive, semi–intensive, and intensive. Lambs in the extensive group were grazed on pasture. Lambs in the semi-intensive group were grazed on pasture and also fed with concentrated feed. The concentrated feed was given to lambs in the intensive group. The experiment was conducted for 90 days. A total of 24 lambs (8 fattening lambs from each group) were slaughtered. While slaughter weights of extensive, semi–intensive, and intensive fattening groups were 32.71, 41.38 and 41.49 kg, respectively (P<0.001), hot carcass weights were 14.24 for extensive group, 19.21 for semi–intensive group, and 20.44 kg for intensive group (P<0.001), and also cold carcass weights were 13.73 for extensive group, 18.79 for semi–intensive group, and 19.94 kg for intensive group (P<0.001). Results of this study revealed that there was generally no statistically significant difference between intensive and semi-intensive groups in terms of slaughter and carcass traits. The results of this study revealed that semi-intensive group can be said to be more appropriate for fattening the male Hemsin lambs.