A well developed and validated RP – HPLC method by UV- detection was used for the determination of Gatifloxacin in human plasma with metronidazole as internal standard. Solid phase extraction was involved in the process. The drug and the internal standard were eluted under isocratic mode using a 150 X 4.6 mm i.d, 5 µm Phenomenex ODS 2 C18 column. The mobile phase composed of a mixture of 5:95 % v/v methanol and 20mM mixed phosphate buffer (pH 3.5± 0.05) at a flow rate of 1.4 mL/Minute. The detection wave length of the detector was 268 nm. A volume of  50 µL was injected and the runtime of the method was 9 minutes. The method showed good linearity in the range of  50.1 to 7000.9 ng/mL. The recovery of gatifloxacin was 92.42 % with a standard deviation of 1.533 and recovery of internal standard was 87.6 %. The LOD of Gatifloxacin was 50.1 ng/mL. Matrix effects were not observed.