An electrosurgical system is provided for the treatment of tissue, the system including an electrosurgical generator (1) for generating a radio frequency (RF) voltage, and an electrosurgical instrument (3) for the vaporization of tissue. The instrument (3) comprises an instrument shaft (10) having a longitudinal axis, and an electrode assembly at one end of the shaft. The electrode assembly comprises a tissue treatment electrode (11) and a return electrode (14, 25) electrically insulated one from another by means of an insulation member (12). The tissue treatment electrode (11) has an exposed surface (19) for treating tissue, the exposed surface of the tissue treatment electrode being laterally disposed on the instrument shaft (10), and being such that it presents a substantially planar face lying in a plane angled at between 120° and 177.5° to the longitudinal axis, with 0° and 180° being the proximal and distal directions of the longitudinal axis. The generator (1) is such that the magnitude of the RF voltage delivered to the tissue treatment electrode (11) is sufficient to cause tissue vaporization when the system is used for tissue treatment.
