The determination of netilmicin sulfate by liquid chromatography using a column packed with poly (styrene-di-vinylbenzene) and pulsed electrochemical detection on a gold electrode is described. The mobile phase consisted of an aqueous solution containing 35 g 1-1 of sodium sulfate, 0.5 g 1-1 of sodium octanesulfonate, 10 ml 1-1 of tetrahydrofuran and 50 ml 1-1 of 0.2 M phosphate buffer (pH 3.0). The total analysis time was not more than 25 min. The effects of the different chromatographic parameters on this selection were also investigated. When a number of commercial samples of netilmicin sulfate was analyzed using this method, eight different components were separated, three of which were of unknown identities.