This investigation was done in the laboratories of the Faculty of Agriculture – Damascus University in the Department of Food Sciences. The aim of this research use to study the inhibition effect of the growth and activity of Lactic acid bacteria used as starter and on the growth of Staph. aureus bacteria. Pure strains of Staph. aureus and Lactic acid bacteria was used the effect of Lactic acid bacteria (Streptococcus thermophilus and Lactobacillus bulgaricus) on the number of Staph. aureus was studied at 37 ◦C and 4◦C. The Lactic acid bacteria were inoculeted in milk for the manufacturing of yoghurt. The number of Staph. aureus was fixed then was decreased gradually according to time. And the decreasing number of this bacteria was clear when S. thermophilus and Lb. bulgaricus were used as a mixture starter, then when was used as a single starter, Lb. bulgaricus and S. thermophilus.