The pharmacokinetic parameters of marbofloxacin were studied following intravenous and oral (single & repeated) administrations in normal and experimentally Escherichia coli infected broiler chicken . Following a single intravenous injection of 5 mg marbofloxacin /kg b.wt. in normal chicken, marbofloxacin could be detected therapeutically for 24 hours post intravenous injection. The serum concentration – time curve of marbofloxacin following intravenous injection showed that the drug obeyed a two compartments open model with elimination half- life (t0.5(β) = 7.98 ± 0.031hours), volume of distribution (Vdss = 1.57 ± 0.214 ml/kg ) and total body clearance of the drug (CLtot = 0.228 ± 0.001L/hr/kg ). Following a single oral administration of 5 mg/kg body weight marbofloxacin in normal chickens , the peak plasma concentration ( Cmax) was 1.21 ± 0.006 µg/ml was achieved at a maximum time ( Tmax) of 2.32 ± 0.011hour . The oral bioavailability of marbofloxacin in normal chicken was 64.28 ± 0.63%.. Oral administration of 5 mg marbofloxacin per kilogram body weight once daily for five consecutive days in normal and Escherichia coli infected chicken revealed a lower significant serum marbofloxacin in Escherichia coli infected chickens compared with normal chickens.