SUMMARY—Gas‐liquid partitioning of head‐space vapors offers possibilities as a quality control procedure, permitting rapid identification of certain bacteria of sanitary and public health significance in foodsRepresentative organisms of the following genera were studied:Escherichia, Salmonella, Citrobacter, Enterobacter, Proteus, AlkaligenesandPseudomonas. The head‐space vapors over synthetic broth cultures were analyzed by gas chromatography in an effort to obtain reproducible patterns differentiating the bacteria. Selected food materials were inoculated with two cultures (Salmonella and Enterobacter) and, after storage at 5°C, the foods were examined by the chromatographic procedure.Analysis of head‐space vapors over dextrose fermenting bacterial cultures by gas‐liquid partitioning produced chromatographic patterns differentiating members of the familyEnterobacteriaceae. Two food materials inoculated with test organisms evidenced presence of Salmonella andEnterobacterwhen submitted to analysis. A third food material was initially contaminated with a mixed flora; gas chromatographic analysis indicated the presence of members of the familyEnterobacteriaceae.It is concluded that gas chromatographic analysis of head‐space is a reproducible method and can be applied to routine microbiological examin