Abstract: An electrosurgical high frequency generator has a high frequency oscillator and, connected thereto, a regulatable power stage to which a patient current circuit with active and neutral electrodes can be connected via an output transformer. Three parameter sensors for the high frequency current, the high frequency voltage and the arc formation are provided at the output circuit and are connected via an interface to a microcomputer which in turn controls the power stage. In accordance with the invention, a tissue impedance sensor is additionally provided which is likewise connected to the microcomputer via the interface.