Abstract: A device for measuring exhaled flow comprises a measuring tube partially obstructed by a narrow part of the tube; and a differential pressure sensor coupled to the tube for measuring the pressures inside the tube on either side of the narrow part. The measuring tube is removable and comprises, at its outer surface, flexible annular seals protruding from the outer surface and located on either side of openings which are in turn located on either side of the narrow part. The measuring tube is insertable in a recess of the device, the recess having a diameter slightly greater than the external diameter of the measuring tube such that, in an abutment position of the measuring tube in the recess, the annular seals define with the recess and the external wall of the tube annular chambers communicating respectively with two passages of the recess, connected to the pressure sensor.