Metronidazole [2-methyl-5-nitroimidazole-1-ethanol] is a nitroimidazol derivative, which is used in the long term therapy for trichomoniasis, amoebiasis and giardiasis. The aim of this study is to validate the analytical method of metronidazole in dog plasma by high pressure liquid chromatography (HPLC) with detector UV (at 320nm) using carbamazepine as an internal standard. After precipating protein in plasma by acetonitrile, metronidazole and internal standard were eluted from RESTEK ultra Cl8 column (5um 250x4,6mm) at 25oC with a mobile phase consisting of acetonitrile and pH 4,5 K2HP04 (30:70 v/v), at a flow rate of 1.0 ml/min. 0,1 percent TEA was added to the mobile phase to help for the elution. The lower limit of quantitative was 0,02 ug/ml with a relative standard deviation of less than 20 percent. A linear range of 0,2 - 40 ug/ml was established. This HPLC method was validated with the precision of 2,70 - 6,35 percent, respectively. The accuracy was 100,68 - 106,49 percent respectively. This validated method is sensitive and repeatable enough to be used in bioavailability studies in dogs.