A device for morcellating tissue within a body cavity of a patient comprises a stationary tube (8) having a distal end portion (12), and a bipolar electrosurgical electrode assembly (13) located at the distal end of the tube. The electrosurgical electrode assembly (13) comprises first and second electrodes (14, 16) separated by an insulating member (15), the bipolar electrosurgical electrode assembly extending around the circumference of the distal edge of the tube (8). When a pulsed electrosurgical cutting voltage is applied to the electrode assembly (13) and relative movement is initiated between the tube (8) and the tissue, a core of severed tissue is formed within the tube such that it can be removed from the body cavity of the patient. Temperature sensors (60) can be used to measure the temperature at the distal end of the tube (8), and to vary the duty cycle of the pulsed cutting voltage.