A dual-purpose study was carried out in an attempt to develop a rapid, sensitive method to identify Neisseria species by gas chromatography and to learn more about the metabolism of these organisms. Sixty-nine isolates of Neisseria were grown in a chemically defined fluid medium; the spent medium was extracted sequentially at pH 2 with diethyl ether and at pH 10 with chloroform. The pH 10 extracts were derivatized with heptafluorobutyric anhydride and analyzed by electron capture gas-liquid chromatography. The resulting spent culture medium electron capture gas-liquid chromatography profiles showed several qualitative and significant quantitative differences among the Neisseria species potentially useful in separating and identifying these organisms. Putrescine and cadaverine which were present in the spent culture medium of some Neisseria, including N. gonorrhoeae, were tentatively identified. Substituting carbohydrates for the chemically defined medium containing glucose in the base medium produced altered profiles with increased quantitative and qualitative differences.