This study aimed to evaluate the effect of replacing soybean meal with sesame meal as a protein source in a concentrate diet treater with thyme on lamb performance and some carcass characteristics. Twentyfour local Awassi male lambs at approximately four months old with an average of 24.6. ± 2.5 kg live body weight was used in this study. After ten days of adaptation, lambs were kept in an individual pen, blocked according to their live body weight, and then randomly divided into four experimental groups (6 lambs/group). The four experimental diet groups created were: soybean meal as a protein source (BC), soybean meal supplemented with 30 g/kg DM thyme (BT). Sesame meal as a protein source (SC). And sesame meal as a protein source supplemented with 30 g/kg DM thyme (ST). Lambs were randomly allocated to receive ad libitum one of the four experimental feeding groups with free access to clean water and wheat straw. Each lamb was slaughtered after it reached 40 kg live weight to study the effects of experimental treatments on slaughter and carcass traits. Data were analysed as Factorial 2 x 2 using GenStat 15 software. The results showed that replacing soybean meal with sesame meal in the diet had a significant effect (P<0.05) on reducing daily dry matter intake (1.16, 1.16, 1.13, 1.12 kg/lamb/day), concentrate intake (0.78, 0.71, 0.65, 0.64 kg/ lamb/day) and increased feed conversion ratio (5.7, 6.0, 6.6 and 7.2 kg/kg for BS, BT, SC and ST respectively). However, using sesame meals as a protein source significantly reduced the cost of the diet. Moreover, using sesame meals in the diet reduces glucose concentration in blood plasma, with no significant effect on carcass and slaughter characteristics. Supplemented 3% of thyme did not have any significant effect on most studied parameters. According to the results, sesame meals can be used in lamb nutrition with some possible reduction in daily feed intake costs.