Abstract: The invention relates to a tracheal cannula for the mechanical respiration of tracheotomised patients having a cuff which encloses and seals the proximal section which can be inserted concentrically in the trachea, a curved section arranged above the cuff and an inner cannula which can be inserted concentrically into the cannula from the distal end thereof, an exhalation opening being provided in the cannula above the cuff sealing the trachea and approximately in the extension of the longitudinal axis of the bent section insertable in the trachea, and, in its region lying beneath the exhalation opening, the inner cannula comprises an opening, which is at least partially covered by an elastic diaphragm acting as a valve, and at its proximal end the inner cannula comprises a region which is constricted in its cross section.