This experiment was carried out to evaluate the effect of different slaughter weights on the fattening performance, slaughter and carcass characteristics of male Karayaka lambs at approximately 4 months of age. Thirty-six lambs, the initial liveweights of which were around 26.5 kg, were divided into 3 groups according to slaughter weight [(Group 1: 35 kg, n = 12), (Group 2: 40 kg, n = 12) and (Group 3: 45 kg, n = 12)] at the beginning of the fattening period. The average daily gain was 203.1, 214.5 and 195.0 g/day, feed conversion efficiency was 7.3, 8.6 and 8.8 kg, and the fattening period was 42.00, 64.67 and 95.08 day in Groups 1-3, respectively. There were significant differences among the groups for average feed conversion efficiency, metabolizable energy, crude protein, and the weight of the head, skin, feet, lung, liver, kidney, internal fat, gastro-intestinal tract and testes (P < 0.05, P < 0.01). The lean, bone and fat weight, backfat thickness and musculus longissumus dorsi area in the carcass increased with increasing slaughter weight.