<p>The invention concerns an osteomedullar biopsy trocar comprising an outer hollow tube provided with a sharpened distal end including an off-center orifice with a diameter smaller than the initial diameter of the tube, and an inner hollow tube located inside the first tube and whereof the distal end includes a sharpened crescent-shaped blade perpendicular to the axis of the trocar and arranged to be positioned laterally on the side opposite the off-center orifice so an to enable bone marrow to be introduced into the trocar during coring and the base of the core to be cut in the trocar axially rotating the inner tube and hence the blade.</p>