Because of its versatility, sensitivity, and ease of operation, gas-liquid chromatography (GLC) is used in almost all aspects of laboratory work where chemical mixtures are separated and analyzed. The ever increasing array of new column packing materials, derivatization procedures, automation, and improvements in detectors makes GLC a desirable technique for the identification of microorganisms. In addition, some viral and noninfectious diseases and changes in host metabolism resulting from infection perhaps could be determined by GLC.