A series of 100 patients suffering from trigeminal neuralgia treated by percutaneous radiofrequency thermocoagulation of the trigeminal ganglion is reported. The authors make some considerations about the basic principles of the thermocoagulation and comment a few important methods of treatment used prior to this new technique. The whole sequency of the surgical procedure is described and its results analysed. The final conclusion is that percutaneous radiofrequency thermocoagulation has become the treatment of choice for trigeminal neuralgia when the clinical treatment is not anymore effective or the side-effects of the drugs contraindicate its use.