Abstract: An apparatus for the measurement of the red blood cell deformability having a measurement cell formed of two electrically insulated compartments clamped mechanically one against the other, with a commercially available multipore membrane therebetween, each of the parts having inlet and outlet orifices as well as a cavity having one electrode and a lateral hole. One of the cavities contains a buffer, the other being intended to receive a suspension of red blood cells consisting of a dilution of a small volume of red blood cells in a large volume of an isotonic conducting buffer, having a volume concentration allowing substantially the transit of a single red blood cell at a time through the multipore membrane, under the action of a device for applying pressure connected to the cavity containing the suspension. An electronic device translates into transit times the electric impedance variations corresponding to the transit of each single red blood cell through the multipore membrane.