A medical instrument for cutting tissue having a tubular outer shaft which, in the area of its distal end, has at least one window with at least one blade, and further comprises a tubular inner shaft which is rotatable about a longitudinal axis, is received in the outer shaft and has, at its distal end, a cutting element which is arranged in the area of the at least one window of the outer shaft and is provided with several circumferentially arranged openings, each of the openings of the cutting element having at least one blade which, when the cutting element is moved in rotation, cooperates in a cutting action with the at least one blade of the outer shaft. It is proposed that at least some of the openings of the cutting element should have different widths, seen in a circumferential direction.
