The present invention refers to a system and a method for the automatic detection of the expiratory flow limitation of a subject. In an embodiment thereof the system for the automatic detection of expiratory flow limitation of a subject comprises determining the respiratory impedance of the subject comprising an imaginary component and, eventually, of a real part or, at least, by applying a forcing signal with one or more spectral components to the airway opening of a subject combined with measuring time courses of pressure and flow at the airway opening; determining at least one index linked to respiratory impedance or pressure and flow time courses; indicating the positioning of at least one index in relation to a preset threshold value.