This experimental study was conducted to determine of ratio of passing of flunixin meglumine into synovial fluid. Five healthy dogs were usedas materials. Flunixin meglumine (FinadynR) was injected intramuscularly (1.1 mg/kg) to each dog. Venous blood and synovial fluid for determination of plasma and synovial fluid flunixin meglumine concentration were collected at 4 and 8 th hours alter drug administration. Concentration of flunixin meglumine in plasma and synovial fluid were analysed by HPLC As a result, ratio of passing of flunixin melumine into synovial fluid was found to be 47% and 23% at 4 and 8 th hours, respectively.