One of the current urgent task in medicine, and preventive medicine in particular, is the development of noninvasive (without surgery) methods of diagnosis and determination of the risks of various diseases. Much attention is paid to the possibilities of exhaled breath analysis for the diagnosis of various diseases such as cancer, gastroenterology, diabetes and others. Possibilities of such analysis are determined by a wide range of human exhaled volatile organic compounds. The growing interest in the development of noninvasive methods of diagnosis of diseases by the analysis of exhaled breath initiated the creation of easy-to-use and portable gas analyzers for the mass examination of patients in non-laboratory conditions. The main requirements for such gas analyzers are combinations of portability, speed, sensitivity and stability control. Current article presents a gas chromatographic method of rapid analysis of exhaled breath with an automated calibration of the vapor-phase concentration source that meets all of the above requirements. A portable polycapillary gas chromatography is used, which provides low thresholds for the determination of substances at the time of analysis of a few tens of seconds. The method of obtaining the vapor-phase calibration concentration of acetone vapors at the level of 10-10 g/cm3 is discussed. The calibration unit is integrated into the gas chromatograph (GC), and its software control ensures the automation of GC calibration. The original scheme of the sampling system (SS) provides multiple input samples from a single exhalation of a person and a completely similar input calibration air mixture in GC to reduce the calibration errors. The structure of the software is implemented in convenient terms for the chemist-analyst practice. Original SS, polycapillary gas chromatography, and built-in automated calibration provide real-time analysis of exhaled air in the presence of the patient. The possibility of differentiation of patients by metabolic disorders (metabolism) in the human body by express analysis of exhaled air using the proposed gas chromatographic method of express analysis of exhaled air with automated calibration is illustrated.