Milk samples and lab-made yoghurt were used to investigate the antibacterial effect of bifidobacteria bifidum on Staphylococcus aureus pathogen. All samples were analyzed microbiologically for presence of S. aureus when fresh and after 2 and 5 days of storage at refrigeration temperature for milk and yoghurt respectively proven to be contaminated with S.aureus from infected, non treated dairy cows and experimentally milk inoculated with S.oureus (5x10⁴ cfu/ml). the obtained results indicated that there were adequate difference in S.oureus count in the examined samples treated with bifidobacteria bifidum from zero time till the 2^nd day of storage in bifudus milk. The reduction of S.aureus were 100% at 2^nd, 3^rd, 4^th and 5^th days of storage in bifidus yoghurt manufactured from inoculated milk with S.aureus. The current study indicates that Bifidobacteria may restrict and/ or inhibit S.aureus in milk and yoghurt.