This study was carried out to investigate the effect of partial replacement of berseem hay by Moringa oliefera stems. Fifteen of lactating Friesian cows with average live body weight of 500 kg and 2-4 seasons of lactation after the peak milk yield were divided into three groups (5 each) assigned randomly to three experimental rations. Control ration (R1) consisted of 40% concentrate feed mixture (CFM) + 20% corn silage (CS) + 20% rice straw (RS) + 20% barseem hay (BH), While the other rations contained 10 and 20% Moringa oliefera stems (MS) instead of 50 and 100% of BH in R2 and R3, respectively. Results revealed that the contents of CP, CF and ash tended to increase, however the contents of DM, OM, EE and NFE tended to decrease with increasing the level of Moringa oliefera stems in the rations. Ration 2 recorded significantly (P<00.05) the highest digestibility coefficients of DM, OM and CP and R3 the highest EE digestibility and DCP value. Average daily feed intake and rumen fermentation activity were nearly similar for the different groups. Total protein, albumin and globulin concentrations increased significantly (P<0.05), however urea-N and creatinine concentrations in plasma decreased significantly (P<0.05) with increasing the level of Moringa stems in the rations. Average daily yield of actual milk and 4% FCM as well as the percentages of fat, protein, total solids and solids not fat in milk increased insignificantly (P<0.05) with increasing the level of Moringastems in the rations. Moringa Stems led to significant decrease (P<0.05) in the amounts of DM and TDN per 1 kg 4% FCM. Also, Moringastems reduced the average daily feed cost and feed cost per one kg 4% FCM, but increased the price of 4% FCM yield and subsequently economic efficiency.