Abstract: Apparatus and methods for ablating, severing, cutting, shrinking, coagulating, or otherwise modifying a target tissue to be treated. In a method for treating a target tissue, an active electrode of an electrosurgical probe is positioned in at least close proximity to the target tissue in the presence of an electrically conductive fluid. A high frequency voltage is then applied between the active electrode and a return electrode, wherein, the high frequency voltage is sufficient to volumetrically remove (ablate), sever, or modify at least a portion of the target tissue. The probe comprises a multi-lumen shaft having a plurality of internal lumens, and a return electrode coil oriented substantially parallel to the shaft distal end. The active electrode may be in the form of a metal disc, a hook, or an active electrode coil. In the latter embodiment, the active electrode coil is typically arranged substantially orthogonal to the return electrode coil.