The present work was performed to study the effect of someantibiotics residues that are most probably used in poultry farms dueto their excess usage either for prophylaxis or treatment. The drugswere administered in the drinking water to study their effect onsome body enzymes and oxidative stress as well as on the growthrate through giving the therapeutic dose to chicken either beinghealthy or infected with Escherichia coli.The study included one hundred and six chicks, one-day old,apparent healthy were classified into 5 groups. Each group wastreated as the following:1 st Group: Control group.2nd Group: Treated with ciprofloxacin 10% in a dose of (10mg/kgb.wt.) in drinking water on day 19 for 5 successivedays.3rd Group: Treated with florfenicol 10% in a dose of (20mg/kgb.wt.) in drinking water on day 19 for 5 successivedays.4th Group: Infected with E.coli strain 01 at day 14 and treated withciprofloxacin 10% in a dose of (10mg/kg b.wt.) for 5successive days.5th Group: Infected with E.coli strain 01 at day and treated withflorfenicol 10% in a dose of (20mg/kg b.wt.) for 5successive days.