Abstract: The method for determination of filcilin by oscillopolarographic titration with Na—tetraphenylborate solution was presented. Excess amount of standard solution of Na—tetraphenylborate was added to the acetate buffer solution (pH =5.3-6.4) containing the sample to precipitate filcilin quantitatively. It was filtered through a dry filter and a measured volume of the filtrate was transferred to a beaker. Adjusting the acidity of the solution to alkaline, the excess Na-tetraphenyl- borate was titrated with standard thallous sulfate solution, using the disapperance of the incision Of Na-tetraphenylborate on dE/dt—E curve to indicate the end point. The method is accurate, rapid and simple, the standard deviation is 0.5%. The excipient and additives presented in tablets do not interfere with the determination.