A detailed analysis shows how electrosurgical r-f power is localized in the vicinity of the cutting electrode. This localization requires a small radius of curvature for the surgical tip, relatively high r-f voltages, and rapid surgical tip motion. The erratic results sometimes encountered in electrosurgery may be due to a deficiency in the above procedures as well as a lack of care in the use of the r-f leads and ground plates. A further analysis supports the supposition that evolving steam bubbles in the tissue at the surgical tip continuously rupture the tissue and are responsible for the cutting mechanism.