Essential amino acids such as methionine have been increasingly included into diets of lambs. However, few studies have determined the effects of methionine supplementation in the general performance and economic returns of lamb production. To address this question, 21 weaned male Rahmani lambs were allotted to 3 dietary treatments: control diet (C), control diet plus 3.30 g of methionine/kg concentrate feed mixture (T1), and control diet plus 3.63 g of methionine/kg concentrate feed mixture (T2). T1-fed lambs showed significantly higher (P < 0.05) total body weight gain than those fed diets C. The digestibility coefficients of dry matter (DM), organic matter (OM), crude protein (CP), ether extract, (EE), and nitrogen free extract (NFE) for T1 and T2 were significantly better (P < 0.05) than for C. Economically, dietary feed T1 and T2 increased the net profit by 329.64 Egyptian pounds (EGP)/lamb and 305.76 EGP/lamb, respectively, as compared with the control diet. In addition, the economic efficiency (average feed cost/kg of body weight gain) was 10.02 for C and T1 and 10.48 for T2. Total costs were similar between the 3 dietary treatments. In conclusion, feeding growing Rahmani lambs with 3.30 g of methionine/kg concentrate feed mixture improved their growth performance and raised their economic value.