The invention relates to a HF surgical instrument for treating, in particular, for cutting and coagulating biological tissue by means of a HF current. The HF surgical instrument comprises a HF generator for supplying a HF current to a cutting electrode and comprises at least one control device for interrupting a HF current circuit. The design of this HF surgical instrument is improved in that a cutting capacity is enhanced. In addition, the control device comprises a current monitoring device that detects the amplitude of the HF current and then generates a first switch-off signal when the HFcurrent decreases over a defined period of time and/or the HF current falls below a threshold value characterizing a state of the treated tissue. The control device also comprises an electric arc monitoring device, which then generates a second switch-off signal when an electric arc occurs between the cutting electrode and the tissue. The control device is designed in such a manner that the HF current circuit is interrupted in response to the first switch-off signal or the second switch-off signal.