The effect of long term (60 days) of onion waste feeding (as economic Source of feed ) on some blood constituents and rumen parameters of 30 non pregnant balady ewes during the interval period was studied at private farm located in Manzala, Dakahlia Governorate. The animals were allocated in 3 equal groups (ten/each) and received (0, 25 and 50%) onion waste on dry matter basis in their ration with supplemental concentrate feed mixture and barseem hay to cover their maintenance nutrient requirement according to NRC (1985). The animals weighed early morning after over night fasting at the beginning and every 30 days post feeding trial. Blood, serum and rumen samples were collected from all animals at 30 and 60 days of feeding trial for laboratory analysis. The results of the present study revealed a picture of anemia which is more evident in sheep fed 50% onion waste due to intravascular haemolysis. Heinz body was detected in blood of sheep fed onion waste with the highest mean value on 30 days. Also reticulocytes was observed in onion waste fed sheep at 30 and 60 days post feeding. The anemia of sheep fed onion waste had evidences by decreased erythrocyte count, haemoglobin concentration and haematocrite value. No significant changes were recorded in the activities of serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), albumin, creatinine, cholesterol, triglycerides, calcium and phosphorus. In contrast the values of blood urea nitrogen and glucose were significantly decreased while the activity of ALP, serum total protein and globulin were increased with onion waste feeding. The mean values of ruminal TVFAs was higher, while ammonia nitrogen concentration were reduced with onion waste feeding when compared with control. The rumen pH not affected. The body weight decreased with high level onion waste feeding when compared with low level onion waste feeding or control. In spite of these alteration, sheep could adapted their physiological mechanisms under the accumulative onion waste feeding stress and survived without any mortality.