A novel version of headspace analysis is substantiated by theory and experiment. The version assumes chromatomembrane extraction of the analyte components into a gas phase. The boundary conditions for the process of chromatomembrane gas extraction are established. Two modes are suggested for analysis with continuous extraction of analyte substances: the mode of ultimate equilibrium saturation and that of total isolation. The advantages of the method in the determination of traces of volatile substances are obvious from its comparison with traditional techniques based on stripping or membrane diffusion.