A urological resectoscope having a tubular shaft (3) is disclosed, having a fixed optical guide tube (2), within which there is an optical system (1) that projects distally beyond the optical guide tube. An elongate, rod-shaped carrier (4) is provided, which carries a cutting instrument (6) at its distal end. The carrier (4) is longitudinally moveably mounted in the tubular shaft (3) outside the optical guide tube (2). The carrier is held distally from the optical guide tube (2) with a sliding tube (8) on the optical system (1) at a radial spacing from the axis of the optical system (1). The carrier is also secured in the peripheral rotary direction to the optical guide tube (2) with a rotary lock (9, 10). The rotary lock has a bar (9) parallel to the carrier (4) and connected to it and a distally open elongate slot (10) in the optical guide tube (2).