Sheep are of great economic value in developing world and considered the mean of life for most families. The lack of information and updates related to acid-base balance, rumen, hematological and serum biochemical parameters in Egyptian Ossimi sheep creates a need for further studies in this area. Therefore, this study was designed to investigate normal acid- base balance parameters, rumen, and blood constituents in healthy Egyptian Ossimi sheep. A total of 30 apparently healthy adult Egyptian Ossimi ewes, their age 3.06 ± 1.33 years and their body weight 35.00±1.19 kg have been used in this study. Blood and Rumen juice samples were collected in the morning before feeding. Blood samples were divided into three parts, the first on EDTA tubes for hematology, the second on plain tubes for serum separation and estimation of serum biochemical parameters, and the third on heparin which send immediately for blood gas analysis. Normal pH of blood and rumen were 7.45 ± 0.02 and7.19 ± 0.16, Total VFAs and ammonia nitrogen concentration were 58.68 ± 4.50 mmol/L and 6.49 ± 0.97 mmol/L respectively. RBCs, WBCs count were 11.44 ± 0.72 ×106 /cmm and 8.13 ± 0.71×103 / cmm. Total protein, albumin, GGT, and BUN were 6.93 ± 0.18 g/dl, 2.84 ± 0.07 g/dl, 25.16 ± 2.15 Units/ml, and 20.60 ± 1.07 mg/dl respectively. These results generally were in accordance with normal reference range of the species. [ABSTRACT FROM AUTHOR]