Investigation the infl uences of vitamin (vit) E over a period of 5 days on the pharmacokinetics of fl orfenicol after single and multiple oral administrations in broiler chickens. Total of 12 broiler chickens had been taken single and multiple oral administrations of fl orfenicol (30 mg/kg) alone or pre-treated with vit E (2 mg/kg). The serum concentrations of fl orfenicol were determined using microbiological assay with Bacillus subtilis (ATCC 25922) as a tested microorganism. The mean serum concentrations of fl orfenicol alone were markedly lower when compared with fl orfenicol pre-treated with vit E after single and multiple dosing. The peak serum concentrations (C max ) were 5.9±0.46, 7.48±0.3 ug/ml, absorption half-life (t 0.5ab ) of 0.51±0.06, 0.71±0.1 h and elimination halflife (t 0.5el ) of 2.72±0.34, 3.34±0.5 after single fl orfenicol alone and fl orfenicol pre-treated with vit E respectively. While, after multiple dosing, (C max ) were 7.4±0.3, 8.04±0.3 ug/ml, (t 0.5ab ) 0.82±0.04, 0.81±0.04 h and (t 0.5 el ) 3.77±0.2, 4.52±0.7 h after multiple dosing of fl orfenicol alone and fl orfenicol pre-treated with vit E respectively. In conclusion Vit E alter the disposition kinetics of fl orfenicol after single and multiple oral administrations as, vit E allows prolongation of the duration of action for more 24 and 48 h of the drug concentration in the serum indicated by prolonged elimination half-lives and MRT refl ecting the importance of this combination for the drug duration in serum but the increase in the serum concentration of fl orfenicol increasing its effi cacy not toxicity as fl orfenicol of wide safety margin so, it's advisable for poultry farms owners to use this combinations.