This study was carried out to evaluate the effects of adding two levels of Rumi live yeast (RLY), which is a commercial probiotic containing yeast on productive performance of Rahmany lambs. Twenty-one Rahmany lambs after weaning at three months of age with an average live body weight of 19.33±0.2 Kg were assigned to three groups according to live body weight (7 lambs each). They were randomly assigned to the three experimental diets. The control group was fed 35% corn silage and 65% concentrate feed mixture on DM basis, without Rumi live yeast addition (R1, control). The other two groups were fed the same control ration along with 3 and 5g RLY/ head/day (R2 and R3, respectively). Addition of RLY significantly (P<0.05) increased average daily gain, all nutrients digestibility, digestibility of cell wall constituents (NDF, ADF, cellulose, hemicellulose) and improved feeding values (TDN and DCP%) and feed conversion. Blood constituents were generally normal in all experimental groups, however, blood plasma total protein, albumin and globulin were significantly (P<0.05) higher for animals fed 3 or 5gm RLY additives rations. Feed conversion efficiency was significantly (P<0.05) improved for lambs fed rations contained 3 or 5g RLY and the effect on daily gain was more pronounced with increasing the levels of RLY compared with the control ration. Results of growth performance showed that there were improvements with respect to total body gain and average daily gain in groups R2 and R3. Also, the best feed and relative economic efficiency were achieved by group fed 5g/h/d yeast followed by group fed 3 g/h/d yeast and the lowest was recorded with control ration. It was concluded that adding 3 or 5g of RLY to rations of growing Rahmany lambs improved their performance, digestibility, average daily gain and feed conversion and the best results were achieved with 5g/h/d supplementation level of RLY.