Mastitis is one of the most common diseases in dairy cattle and causes great economic loss to the dairy industry', this study will shine a spotlight on Staphylococcus aureus isolates with particular reference to MRSA strains from milk of mastitic cows, as well as its in-vitro antimicrobial sensitivity. And biochemical blood changes. Our result indicates that out of 300 samples of quarter milk from cows showing signs of mastitis, 50 blood samples from mastitic cows and 10 blood samples from apparently healthy contact cows in Giza Provence; the results show that S. aureus was isolated from 100/300 samples with an incidence of 33.3%. of which 36/100 strains are Antibiotic resistant to at least one antibiotic was obtained through the results of antibiotic sensitivity tests. 10/100 strains of S. aureus were multi-drug resistant to more than three Antibiotics. 8/100 of strains are confirmed methicillin-resistant Staphylococcus aureus (MRSA) by Vitek 2 Compact System's declaration and the presence of the resistance MecA gene in MRSA strains was confirmed by PCR results. Significant increases in WBCs, neutrophils, lymphocytes, malondialdehyde, total protein, and globulin, AST, ALT, and ALP are also caused by mastitis. Mastitis also causes a significant decrease in RBCs, Hb, PCV percent albumin/globulin (A/G ratio), catalase, and super oxide dismutase. It is possible to draw the conclusion that mastitis has a negative impact on the hemogram, liver, and kidney functions of cattle in a number of ways.