Localized hyperthermia combined with radiation was applied to selected patients who had tumor known to be refractory to conventional treatment modalities. Hyperthermia was administered by 2,450 MHz microwave or 13.56 MHz radiofrequency according to the site of tumors. In most patients intratumor temperatures of 43 degrees C for 30 minutes was administered twice weekly immediately after irradiation with 4 Gy. A complete regression was obtained in 31 out of 54 lesions (57.5%). The results of our study have shown that localized hyperthermia in combination with radiation is an effective and safe modality for the treatment of radioresistant cancers.