Ninety days feeding trial was conducted with the aim to evaluate the impact of replacing concentrate mix with dried khat (Catha edulis) leftover meal on feed intake, body weight change and digestibility of Tigray Highland sheep fed a basal diet of mixed grass hay. The trial was carried out using 24 lambs (17.8±1.08 kg) with six blocks and four treatments in a randomized complete block design (RCBD). Concentrates mix was substituted with khat leftover meal at a ratio of 0% (T1), 15% (T2), 30% (T3) and 45% (T4) on DM basis. The dietary rations were formulated in iso-nitrogenous to meet the nutrient requirements of lambs. Data was analyzed by analyses of variance (ANOVA) using the General Linear Model (GLM) procedures of SAS (2008). Treatment means comparison was done using Tukey's HSD test at P<0.05. Dried khat leftover meal had moderate crude protein (12.3%) and less NDF value (31.9%). Substituted concentrates mix with 15% khat leftover meal had better impact (P<0.001) on lamb's total DM, OM, ME, ADL and ADF intake compared to the lambs dietary T3 and T4. Daily weight gain and feed conversion efficiency were significant (P<0.001) till substituted concentrates mix with 30% khat leftover meal. Diet digestibility showed reducing as inclusion level of khat meal increased across treatment. It is concluded that khat leftover meal can be utilized up to 30% without deleterious effect on animal performance and health.