BACKGROUND: Colibacillosis in poultry, reduces growth and performance, increases mortality and causes economic losses. ObjectiveS: An experiment was conducted to study the effect of egg yolk powder and antibody (IgY) on intestinal morphology and reduction of bacterial colonization in broilers infected with E. coli. Methods: Ten laying hens were immunized with E. coli O2: K1. The eggs were collected for providing IgY antibody and egg yolk powder with freeze dryer. In the second experiment,180 day-old broilers were randomly divided into 6 treatment groups with 3 replicates of 10 birds per replicate including: (1) positive control (challenged with E.coli but did not receive antibody); (2) negative control (did not challenge with E.coli and did not receive antibody); (3) the group was challenged with E.coli and received 0.4% yolk powder; (4) the group received specific antibody in drinking water and challenged with E. coli; (5) the group received specific antibody in drinking water; (6) the group received 0.4% yolk powder in diet. All groups received the same dietary energy and protein. FI, WG and FCR were measured on weekly basis. On days 21 and 42, one bird per pen was euthanized, samples of jejunum were collected for histo-morphological examination and samples of ileal contents were collected for E. coli O2: K1 enumeration. Results: The results indicated that number of E. coli in positive group was significantly higher than other groups. Number of E. coli in ileum of the birds which received antibody in drinking water or fed with diet supplemented with egg yolk powder was significantly lower than the other infected groups (p|£|0.05). Using specific antibody improved intestinal health compared to positive control group. ConclusionS: According to results of this experiment it can be concluded that using E. coli specific antibody in food or water of chickens reduces intestinal colonization of this bacterium.