Abstract: Florfenicol (FFC) is a synthetic antibiotic with a broad antibacterial spectrum and therapeutic effectiveness. It was specifically developed for veterinary use, with proven value in the treatment of respiratory and enteric infections in food animals. It is active against many chloramphenicol and thiamphenicol-resistant strains. In the present study, serum and tissue residual level of FFC and histopathological investigation of liver tissue after oral administration of 30 mg⁄kg bw and 60 mg/kg bw (5 consecutive days) to broiler chickens were studied. A validated high performance liquid chromatography (HPLC) method with photodiode array detector (PAD) at a wavelength of 223 nm was used for the determination of FFC concentration. Samples were extracted with ethyl acetate and defatted with hexane, followed by clean-up and chromatographic separation on hypersil gold (C18) column with acetonitrile: water as a mobile phase. The residual analysis resulted that FFC concentration in liver was higher than the concurrent serum and muscle concentrations. On 7th day, although the level of FFC was very low, but still detectable in the serum and muscle, on the other hand the concentration in liver declined but still high especially in 60 mg/kg bw treated group. FFC tissue and serum level in 60 mg/kg bw treated group was significantly increased compared with that of the 30 mg/kg bw treated group. Liver FFC level was below the maximum residue limits (MRLs) in both treated groups all over the studied time course, while muscle tissue FFC level was higher than the MRLs at 3rd day post administration, then the level depleted to be below the MRLs at 5th day in the 30 mg/kg bw treated group and at 7th day in the 60 mg/kg bw treated group. The histopathological investigation showed microscopically alterations in liver tissue which appeared to be more serious in 60 mg/kg bw treated groups than that received the therapeutic dose (30 mg/kg bw). The current study concluded that it is necessary to ensure that the residues of FFC were less than the MRLs to guarantee its safety to consumer.