A single dose of florfenicol (20mg/kg b.w.) were injected either i.v., i.m. or s.c respectively for 3 groups of apparently healthy sheep (five animals of each) for comparing its pharmacokinetic properties. The drug concentrations in serum samples were measured for 24h using HPLC with fluorescence detection. Results showed a rapid absorption for the drug reaching to maximum serum concentrations(4.86 and 1.12mg/ml) during 2h after i.m. or s.c. injections while the distribution and elimination half-lives were 3.20, 2.95, 2.85 and 3.21, 3.01, 2.81 after i.v., i.m. and s.c injections respectively which clearly revealed the high and prolonged levels were with i.m. injection. The drug plasma levels were maintained more than or equal to MIC recorded for major pathogenic bacteria causing diseases in sheep (specially respiratory ones) for 24h or more. The study concluded that, florfenicol is a good drug for treating sheep diseases caused by bacteria sensitive to it and one i m. dose (20mg/kg. b.w.) every 24h is enough.