An electrosurgical system is provided for the treatment of tissue, the system comprising an electrosurgical generator (1) and an instrument (3) comprising an instrument shaft (10) having a longitudinal axis, and an electrode assembly (12) at one end of the shaft. The electrode assembly (12) comprises a first tissue treatment electrode (11), a second tissue treatment electrode (14), and first and second return electrodes (24, 25) electrically insulated from the first and second tissue treatment electrodes by means of insulation members (12, 15). The first and second tissue treatment electrodes (11, 14) each have an exposed surface for treating tissue, the exposed surface of the first tissue treatment electrode (11) being such as to treat tissue disposed on the longitudinal axis, and the exposed surface of the second tissue treatment electrode (14) being such as to is treat tissue disposed laterally of the longitudinal axis. The instrument has a first set of connections (62A, 62C) by which the first tissue treatment electrode (11) can be placed in circuit with the first return electrode (24) such that, in use, a current path is established between the first tissue treatment electrode (11) and the first return electrode (24). The instrument has a second set of connections (62B, 62D) by which the second tissue treatment electrode (14) can be placed in circuit with the second return electrode (25) such that, in use, a current path is established between the second tissue treatment electrode (14) and the second return electrode (25).組織処置用の電気外科用システムが提供され、該システムは、電気外科用ジェネレータ(1)と、長手方向軸を有する器具シャフト(10)およびこのシャフトの一端にある電極アセンブリ(12)を備える器具(3)とを備える。電極アセンブリは、第1の組織処置電極(11)と、第2の組織処置電極(14)と、第1および第2の組織処置電極から絶縁部材によって電気的に絶縁された第1および第2のリターン電極(24、25)とを備える。第1および第2の組織処置電極は各々露出した表面を有し、第1の組織処置電極の露出した表面は長手方向軸上に配置された組織を処置するものであり、第2の組織処置電極の露出した表面は、長手方向軸の側方に配置された組織を処置するものである。器具は、第1のリターン電極を有する回路内に組織処置電極を配置するか、または第2のリターン電極を有する回路内に第2の処置電極を配置することができるスイッチを備える。
