A head-space gas chromatographic technique for the analysis of volatile bacterial metabolites is described. Bacteroides fragilis, Clostridium perfringens, and Propionibacterium acnes, cultured in a glucose-containing peptone yeast extract medium, were studied. The head-space technique was compared with the injection of the complete liquid culture medium, and solvent extracts thereof, into the gas chromatograph. Volatile fatty acids could be detected by all three methods, whereas alcohols produced by C. perfringens and P. acnes were detectable only in the head-space chromatograms. Both FFAP and Porapak Q were used as gas chromatography stationary phase. Porapak Q was found more suitable than FFAP for the separation of alcohols. The head-space technique requires a minimum of preparation before the analysis and is well suited to automation.