The treatment effect of radiotherapy combined with local hyperthermia for nasopharyngeal carcinoma was studied in 23 patients. In 24 cases of the control group (radiotherapy), conventionally dynamic fractionation of dose was used. At 40 Gy, the regression of tumor was observed 83% in the study group and 54% in the controls group. No severe complications in patients treated by thermotherapy were noted. This paper discusses the role and the mechanism of local hyperthermia as a rediomodifying factor.