The invention relates to a combined ultrasound and HF surgical system, including at least one ultrasound generator which operatively provides an excitation signal through which an ultrasound converter can generate an ultrasound vibration, at least one HF generator which operatively generates HF energy, and at least one ultrasound and HF instrument electrically connected with the HF generator and the ultrasound generator, wherein the ultrasound vibrations and the HF energy are introducible into biological tissue through the HF instrument which includes at least one ultrasound converter and at least one HF electrode. In order to be able to use HF energy and ultrasound energy simultaneously without damaging the instrument or wearing the it out, the system includes a protective device which prevents sparks operatively generated through HF energy or reduces the probability of occurrence of the sparks.超音波変換器（１３）に超音波振動を発生可能とさせる励起信号を供給する少なくとも１つの超音波発生器（２）と、ＨＦエネルギーを発生する少なくとも１つのＨＦ発生器（３）と、ＨＦ発生器（３）および超音波発生器（２）に電気的に接続された少なくとも１つの超音波およびＨＦ処置具（４）と、を備える超音波およびＨＦ複合型手術用システム（１）であって、該システムは、少なくとも１つの超音波変換器（１３）および少なくとも１つのＨＦ電極（１５）を有するＨＦ処置具（４）によって、生体組織（１７）に超音波振動およびＨＦエネルギーを導入可能であり、ＨＦエネルギーにより発生するスパークを防ぐか、または、該スパークの発生確率を減少させる保護装置（１９）を備える。
