The present study was carried out to determine the influence of dietary probiotic source feed (fungal-yeast; Saccharomyces cerevisiae) on the ability of E. coli 0157:H7 to attach and efface healthy young broilers at different feeding periods (7, 10, 14, 21, and 28 days of age). There were reductions in bacterial attachment of broilers fed various yeast levels. Twenty one days post-challenging about 87% of the (G1); positive control, chicks fed control diet containing 0.00% baker yeast and challenged with E. coli 0157:H7, showed both cecal attachment and effacement. On the other hand  37% of the (G2); chicks fed control diet containing 0.75% baker yeast and challenged with E. coli 0157:H7, showed cecal attachment. And only 16% of the (G3); chicks fed control diet containing 1.00% baker yeast and challenged with E. coli 0157:H7  showed cecal attachment. The results of this study suggest adding yeast at 1.0% into broilers diets causing a significant (P<0.005) decrease in bacterial attachment and may enhance the productive performance and nutrients utilization via the inhibitory effect of yeast against pathogenic bacteria E. coli 0157:H7.